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Modern 
Electronic 



^•[•r~ 



Manual 



Markus 



MODERN 

ELECTRONIC 

CIRCUITS 

REFERENCE 

MANUAL 



Over 3,630 modern electronic circuits, each complete 

with values of all parts and performance details, 

organized in 103 logical chapters for quick 

reference and convenient browsing 



JOHN MARKUS 

Consultant, McGraw-Hill Book Company 

Senior Member, Institute of Electrical and Electronics Engineers 



McGRAW-HILL BOOK COMPANY 

New York St. Louis San Francisco Auckland Bogota Hamburg 
Johannesburg London Madrid Mexico Montreal New Delhi 
Panama Paris Sao Paulo Singapore Sydney Tokyo Toronto 



Library of Congress Cataloging in Publication Data 

Markus, John, date. 

Modern electronic circuits reference manual. 

"Over 3630 modem electronic circuits, each complete 
with values of all parts and performance details, 
organized in 103 logical chapters for quick reference 
and convenient browsing." 

Includes bibliographical references and indexes. 

1. Electronic circuits — Handbooks, manuals, etc. 
2. Integrated circuits — Handbooks, manuals, etc. 
I. Title. 

TK7867.M345 621.3815'3 79-22096 

ISBN 0-07-040446-1 



Copyright © 1980 by McGraw-Hill, Inc. All rights reserved. Printed 
in the United States of America. No part of this publication may be 
reproduced, stored in a retrieval system, or transmitted, in any form 
or by any means, electronic, mechanical, photocopying, recording, or 
otherwise, without the prior written permission of the publisher. 

34567890 KPKP 8987654321 



The editors for this book were Tyler G. Hicks and Joseph Williams 
and the production supervisor was Sally Fliess. It was set in Univers 
65 by University Graphics, Inc. 

Printed and bound by The Kingsport Press. 



Contents 



Preface vii 33. 

Abbreviations used ix 

Semiconductor symbols used . . xiii 34. 

Addresses of sources used xv 

1. Amplifier circuits 1 35. 

2. Antenna circuits 15 

3. Audio amplifier circuits ... 32 36. 

4. Audio control circuits 52 

5. Audio measuring circuits 70 37. 

6. Automatic gain control 38. 
circuits 76 39. 

7. Automotive circuits 81 40. 

8. Battery-charging circuits .. 92 41. 

9. Burglar alarm circuits 101 42. 

10. Capacitance measuring 43. 
circuits 112 44. 

11. Cathode-ray circuits 122 45. 

12. Clock signal circuits 130 46. 

13. Code circuits 141 47. 

14. Comparator circuits 161 48. 

15. Contact bounce suppression 49. 
circuits 170 50. 

16. Converter circuits — analog- 51. 
to-digital 174 52. 

17. Converter circuits — DC to 53. 
DC 188 54. 

18. Converter circuits — digital- 55. 
to-analog 198 56. 

19. Converter circuits — 57. 
general 205 58. 

20. Converter circuits — radio 219 59. 

21. Counter circuits 234 

22. Current control circuits : . . 244 60. 

23. Data transmission circuits 248 61. 

24. Digital clock circuits 261 62. 

25. Display circuits 277 63. 

26. Fiber-optic circuits 299 64. 

27. Filter circuits — active 305 65. 

28. Filter circuits — passive . . . 333 66. 

29. Fire alarm circuits 338 67. 

30. Flasher circuits . . . 343 68. 

31. Frequency counter circuits 352 69. 

32. Frequency divider circuits . 365 70. 



Frequency measuring 71. 

circuits 371 72. 

Frequency modulation 73. 

circuits 383 

Frequency multiplier 74. 

circuits 399 75. 

Frequency synthesizer 76. 

circuits 406 77. 

Function generator circuits 416 

Game circuits 435 78. 

IF amplifier circuits 444 79. 

Instrumentation circuits . . 452 80. 

Integrator circuits 468 81. 

Intercom circuits 473 82. 

Keyboard circuits 479 83. 

Lamp control circuits 489 84. 

Limiter circuits 495 

Logarithmic circuits 499 85. 

Logic circuits 507 86. 

Logic probe circuits 516 87. 

Medical circuits 523 88. 

Memory circuits 533 

Microprocessor circuits . . . 544 89. 

Modulator circuits 558 90. 

Motor control circuits 567 91. 

Multiplexer circuits 582 92. 

Multiplier circuits 595 93. 

Multivibrator circuits 605 

Music circuits 622 94. 

Noise circuits 637 

Operational amplifier 95. 

circuits 644 96. 

Optoelectronic circuits . . . 660 97. 

Oscillator circuits — AF 668 98. 

Oscillator circuits — RF 679 99. 

Phase control circuits 696 100. 

Phonograph circuits 703 

Photoelectric circuits 711 101. 

Photography circuits 715 

Power control circuits 722 102. 

Power supply circuits 735 103. 

Programmable circuits . . . 744 

Protection circuits 754 



Pulse generator circuits . . . 760 

Receiver circuits 776 

Regulated power supply 

circuits 803 

Regulator circuits 827 

Remote control circuits . . . 858 

Repeater circuits 866 

Resistance measuring 

circuits 873 

Sampling circuits 881 

Servo circuits 890 

Signal generator circuits . . 897 

Single-sideband circuits . . 913 

Siren circuits 922 

Squelch circuits 928 

Staircase generator 

circuits 933 

Stereo circuits 940 

Sweep circuits 949 

Switching circuits 956 

Switching regulator 

circuits 964 

Tape recorder circuits 983 

Telephone circuits 997 

Teleprinter circuits 1008 

Television circuits 1024 

Temperature control 

circuits 1039 

Temperature measuring 

circuits 1049 

Test circuits 1064 

Timer circuits 1081 

Touch-switch circuits 1101 

Transceiver circuits 1108 

Transmitter circuits 1123 

Voltage-controlled oscillator 

circuits 1151 

Voltage-level detector 

circuits 1 158 

Voltage measuring circuits 1166 

Voltage reference circuits 1186 

Author index 1195 

Subject index 1203 




MCMCCVII 



Preface 



Over 3,630 practical modem electronic circuits are arranged here in 103 logical 
chapters for convenient browsing and reference by electronics engineers, tech- 
nicians, students, microprocessor enthusiasts, amateur radio fans, and experi- 
menters. Each circuit has type numbers or values of all significant components, 
an identifying title, a concise description, performance data, and suggestions for 
other applications. At the end of each description is a citation giving the title of 
the original article or book, its author, and the exact location of the circuit in the 
original source. 

This fourth in a series of state-of-the-art reference volumes illustrates dra- 
matically the accelerated trend to integrated circuits that has taken place since 
publication of "Guidebook of Electronic Circuits" in 1974. About half of the 
applications now use ICs, and tube circuits have become a distinct rarity. This 
trend becomes even more evident when comparing circuits with those in the 
first and second books of the series, "Sourcebook of Electronic Circuits" and 
"Electronic Circuits Manual." The four books supplement each other and to- 
gether provide a total of over 13,300 different practical circuits at a cost of only 
about 1 cent per circuit. The collection can serve as a basic desktop reference 
library that will match retrieval speeds of computer-based indexing systems 
while providing in addition the actual circuit diagrams. 

The circuits for this new book were located by cover-to-cover searching of 
back issues of U.S. and foreign electronics periodicals, the published literature 
of electronics manufacturers, and recent electronics books, together filling well 
over 100 feet of shelving. This same search would take weeks or even months, 
at a large engineering library, plus the time required to write for manufacturer 
literature and locate elusive sources. 

Engineering libraries, particularly in foreign countries, have found these 
circuit abstracts to be a welcome substitute for the original sources when facing 
limitations on budgets, shelving, or search manpower. As further evidence of 
their usefulness in other countries, some of the books have been translated into 
Greek, Spanish, or Japanese. 

Entirely new chapters in this book, further emphasizing evolution of the 
industry in recent years, include Clock Signal, Fiber-Optic, Game, Keyboard, 
Logic Probe, Microprocessor, Programmable, Switching Regulator, and Touch- 
Switch Circuits. Significant new circuits appear in chapters found also in pre- 
vious books, particularly for Automotive, Burglar Alarm, Digital Clock, Fire 
Alarm, Flasher, Frequency Counter, Frequency Synthesizer, Instrumentation, 
Intercom, Lamp Control, Medical, Memory, Motor Control, Music, Power Con- 
trol, Protection, Siren, Stereo, and Telephone Circuits. 



To find a desired circuit quickly, start with the alphabetically arranged table 
of contents at the front of the book. Note the chapters most likely to contain the 
desired type of circuit, and look in these first. Remember that most applications 
use combinations of basic circuits, so a desired circuit could be in any of several 
different chapters. Scope notes following chapter titles define the basic circuits 
covered and sometimes suggest other chapters for browsing. 

If a quick scan does not locate the exact circuit desired, use the index at the 
back of the book. Here the circuits are indexed in depth under the different 
names by which they may be known. Hundreds of cross-references in the index 
aid searching. The author index will often help find related circuits after one 
potentially useful circuit is found, because authors tend to specialize in certain 
circuits. 

Values of important components are given for every circuit because these 
help in reading the circuit and redesigning it for other requirements. The de- 
velopment of a circuit for a new application is speeded when design work can 
be started with a working circuit, instead of starting from scratch. Research and 
experimentation are thereby cut to a minimum, so even a single use of this cir- 
cuit-retrieval book could pay for its initial cost many times over. Drafting errors 
on diagrams are minimized because any corrections pointed out in subsequently 
published errata notices have been made; this alone can save many frustrating 
hours of troubleshooting. 

This book is organized to provide a maximum of circuit information per 
page, with minimum repetition. The chapter title at the top of each right-hand 
page and the original title in the citation should therefore be considered along 
with the abstract when evaluating a circuit. 

Abbreviations are used extensively to conserve space. Their meanings are 
given after this preface. Abbreviations on diagrams and in original article tides 
were unchanged and may differ slightly, but their meanings can be deduced by 
context. 

Mailing addresses of all cited original sources are given at the front of the 
book, for convenience in writing for back issues or copies of articles when the 
source is not available at a local library. These sources will often prove useful 
for construction details, performance graphs, and calibration procedures. 

To Joan Fife, student at the University of Santa Clara, goes credit for typing 
the complete manuscript directly from dictation while correcting this author's 
grammar and punctuation practices of yesteryear and even catching technical 
oversights. Handling of hyphenation, abbreviations, and citations was entirely 
her responsibility, along with final editing, markup for the printer, and 
production of the index. 

To the original publications cited and their engineering authors and editors 
should go major credit for making possible this fourth encyclopedic contribution 
to electronic circuit design. The diagrams have been reproduced directly from 
the original source articles, by permission of the publisher in each case. 



John Markus 



Abbreviations Used 



A 


ampere 


CRO 


cathode-ray 


F 


farad 


AC 


alternating current 




oscilloscope 


°F 


degree Fahrenheit 


AC/DC 


AC or DC 


CROM 


control and read-only 


FET 


field-effect transistor 


A/D 


analog-to-digital 




memory 


FIFO 


first-in first-out 


ADC 


analog-to-digital 


CRT 


cathode-ray tube 


FM 


frequency 




converter 


CT 


center tap 




modulation 


AID, D/A 


analog-to-digital, or 


CW 


continuous wave 


4PDT 


four-pole double- 




digital-to-analog 


D/A 


digital-to-analog 




throw 


ADP 


automatic data 


DAC 


digital-to-analog 


4PST 


four-pole single- 




processing 




converter 




throw 


AF 


audio frequency 


dB 


decibel 


FS 


full scale 


AFC 


automatic frequency 


dBC 


C-scale sound level 


FSK 


frequency-shift 




control 




in decibels 




keying 


AFSK 


audio frequency-shift 


dBm 


decibels above 1 mW 


ft 


foot 




keying 


dBV 


decibels above 1 V 


ft/mm 


foot per minute 


AFT 


automatic fine 


DC 


direct current 


ft/s 


foot per second 




tuning 


DC/DC 


DC to DC 


ft 2 


square foot 


AGC 


automatic gain 


DCTL 


direct-coupled 


F/V 


f req u ency-to- voltag e 




control 




transistor logic 


F/V, V/F 


frequency-to-voltage. 


Ah 


ampere-hour 


diac 


diode AC switch 




or voltage-to- 


ALU 


arithmetic-logic unit 


DIP 


dual in-line package 




frequency 


AM 


amplitude 


DMA 


direct memory 


G 


giga- (10 9 ) 




modulation 




access 


GHz 


gigahertz 


AM/FM 


AM or FM 


DMM 


digital multimeter 


G-M tube 


Geiger-Mueller tube 


AND 


type of logic circuit 


DPDT 


double-pole double- 


h 


hour 


AVC 


automatic volume 




throw 


H 


henry 




control 


DPM 


digital panel meter 


HF 


high frequency 


b 


bit 


DPST 


double-pole single- 


HFO 


high-frequency 


BCD 


binary-coded decimal 




throw 




oscillator 


BFO 


beat-frequency 


DSB 


double sideband 


hp 


horsepower 




oscillator 


DTL 


diode-transistor logic 


Hz 


hertz 


b/s 


bit per second 


DTL/TTL 


DTL or TTL 


IC 


integrated circuit 


C 


capacitance; 


DUT 


device under test 


IF 


intermediate 




capacitor 


DVM 


digital voltmeter 




frequency 


°C 


degree Celsius; 


DX 


distance reception; 


IGFET 


insulated-gate FET 




degree Centigrade 




distant 


IMD 


intermodulation 


CATV 


cable television 


EAROM 


electrically alterable 




distortion 


CB 


citizens band 




ROM 


IMPATT 


impact avalanche 


CCD 


charge-coupled 


EBCDIC 


extended binary- 




transit time 




device 




coded decimal 


in 


inch 


CCTV 


closed-circuit 




interchange code 


in/s 


inch per second 




television 


ECG 


electrocardiograph 


in 2 


square inch 


cm 


centimeter 


ECL 


emitter-coupled logic 


I/O 


input/output 


CML 


current-mode logic 


EDP 


electronic data 


IR 


infrared 


CMOS 


complementary MOS 




processing 


JFET 


junction FET 


CMR 


common-mode 


EKG 


electrocardiograph 


k 


kilo- (10 3 ) 




rejection 


EMF 


electromotive force 


K 


kilohm (,000 ohms); 


CMRR 


common-mode 


EMI 


electromagnetic 




kelvin 




rejection ratio 




interference 


kA 


kiloampere 


cm 2 


square centimeter 


EPROM 


erasable PROM 


kb 


kilobit 


coax 


coaxial cable 


ERP 


effective radiated 


keV 


kiloelectronvolt 


COHO 


coherent oscillator 




power 


kH 


kilohenry 


COR 


carrier-operated 


ETV 


educational 


kHz 


kilohertz 




relay 




television 


km 


kilometer 


COS/MOS 


complementary- 


eV 


electronvolt 


kV 


kilovoit 




symmetry MOS 


EVR 


electronic video 


kVA 


kilovoltampere 




(same as CMOS) 




recording 


kW 


kilowatt 


CPU 


central processing 


EXCLUSIVE-OR 


type of logic circuit 


kWh 


kilowatthour 




unit 


EXCLUSIVE- 




L 


inductance; inductor 


CR 


cathode ray 


NOR 


type of logic circuit 


LASCR 


light-activated SCR 



ABBREVIATIONS 



LASCS 


light-activated SCS 


NMOS 


N-channei MOS 


QRP 


low-power amateur 


LC 


inductance- 


NOR 


type of logic circuit 




radio 




capacitance 


NPN 


negative-positive- 


R 


resistance; resistor 


LCD 


liquid crystal display 




negative 


RAM 


random-access 


LDR 


light-dependent 


NPNP 


negative-positive- 




memory 




resistor 




negative-positive 


RC 


resistance- 


LED 


light-emitting diode 


NRZ 


nonreturn-to-zero 




capacitance 


LF 


low frequency 


NRZI 


nonreturn-to-zero- 


RF 


radio frequency 


LIFO 


last-in first-out 




inverted 


RFI 


radio-frequency 


Im 


lumen 


ns 


nanosecond 




interference 


LO 


local oscillator 


NTSC 


National Television 


RGB 


red/green/blue 


logamp 


logarithmic amplifier 




System 


RIAA 


Recording Industry 


LP 


long play 




Committee 




Association of 


LSB 


least significant bit 


nV 


nanovolt 




America 


LSI 


large-scale 


nW 


nanowatt 


RLC 


resistance- 




integration 


OEM 


original equipment 




inductance- 


m 


meter; milli- (10~ 3 ) 




manufacturer 




capacitance 


M 


mega- (10 6 ); meter 


opamp 


operational amplifier 


RMS 


root-mean-square 




(instrument); 


OR 


type of logic circuit 


ROM 


read-only memory 




motor 


P 


pico- (Ifr 12 ) 


rpm 


revolution per 


mA 


milliampere 


P 


peak; positive 




minute 


Mb 


megabit 


PA 


picoampere 


RTL 


resistor-transistor 


MF 


medium frequency 


PA 


public address 




logic 


mH 


millihenry 


PAL 


phase-alternation 


RTTY 


radioteletype 


MHD 


magnetohydro- 




line 


RZ 


return-to-zero 




dynamics 


PAM 


pulse-amplitude 


s 


second 


MHz 


megahertz 




modulation 


SAR 


successive- 


mi 


mile 


PC 


printed circuit 




approximation 


mike 


microphone 


PCM 


pulse-code 




register 


min 


minute 




modulation 


SAW 


surface acoustic 


mm 


millimeter 


PDM 


pulse-duration 




wave 


modem 


modulator- 




modulation 


SCA 


Subsidiary 




demodulator 


PEP 


peak envelope power 




Communications 


mono 


monostable 


PF 


picofarad 




Authorization 


MOS 


metal-oxide 


PF 


power factor 


scope 


oscilloscope 




semiconductor 


phono 


phonograph 


SCR 


silicon controlled 


MOSFET 


metal-oxide 


PIN 


positive-intrinsic- 




rectifier 




semiconductor 




negative 


SCS 


silicon controlled 




FET 


PIV 


peak inverse voltage 




switch 


MOST 


metal-oxide 


PLL 


phase-locked loop 


S-meter 


signal-strength 




semiconductor 


PM 


permanent magnet; 




meter 




transistor 




phase modulation 


S/N 


signal-to-noise 


MPU 


microprocessing unit 


PMOS 


P-channel MOS 


SNR 


signal-to-noise ratio 


ms 


millisecond 


PN 


positive-negative 


SPDT 


single-pole double- 


MSB 


most significant bit 


PNP 


positive-negative- 




throw 


MSI 


medium-scale 




positive 


SPST 


single-pole single- 




integration 


PNPN 


positive-negative- 




throw 


m 2 


square meter 




positive-negative 


SSB 


single sideband 


M 


micro- (10~ 6 ) 


pot 


potentiometer 


SSI 


small-scale 


/uA 


microampere 


P-P 


peak-to-peak 




integration 


M F 


microfarad 


PPI 


plan-position 


SSTV 


slow-scan television 


juH 


microhenry 




indicator 


SW 


shortwave 


fim 


micrometer 


PPM 


parts per million; 


SWL 


shortwave listener 


M P 


microprocessor 




pulse-position 


SWR 


standing-wave ratio 


JUS 


microsecond 




modulation 


sync 


synchronizing 


/*V 


microvolt 


preamp 


preamplifier 


T 


tera- (10 12 ) 


liW 


microwatt 


PRF 


pulse repetition 


TC 


temperature 


mV 


millivolt 




frequency 




coefficient 


MVBR 


multivibrator 


PROM 


programmable ROM 


THD 


total harmonic 


mW 


milliwatt 


PRR 


pulse repetition rate 




distortion 


n 


nano- (10~ 9 ) 


ps 


picosecond 


TR 


transmit-receive 


N 


negative 


PSK 


phase-shift keying 


TRF 


tuned radio 


nA 


nanoampere 


PTT 


push to talk 




frequency 


NAB 


National Association 


PUT 


programmable UJT 


triac 


triode AC 




of Broadcasters 


pW 


pico watt 




semiconductor 


NAND 


type of logic circuit 


PWM 


pulse-width 




switch 


nF 


nanofarad 




modulation 


TTL 


transistor-transistor 


nH 


nanohenry 


Q 


quality factor 




logic 



ABBREVIATIONS 



TTY 


teletypewriter 


V 


volt 


VSWR 


voltage standing- 


TV 


television 


VA 


voltampere 




wave ratio 


TVI 


television 


VAC 


volts AC 


VTR 


videotape recording 




interference 


VCO 


voltage- controlled 


VTVM 


vacuum-tube 


TVT 


television typewriter 




oscillator 




voltmeter 


TWX 


teletypewriter 


VDC 


volts DC 


VU 


volume unit 




exchange service 


V/F 


voltage-to-frequency 


WC 


voltage-variable 


UART 


universal 


VFO 


variable-frequency 




capacitor 




asynchronous 




oscillator 


VXO 


variable-frequency 




receiver- 


VHF 


very high frequency 




crystal oscillator 




transmitter 


VLF 


very low frequency 


W 


watt 


UHF 


ultrahigh frequency 


VMOS 


vertical metal-oxide 


Wh 


watthour 


UJT 


unijunction 




semiconductor 


WPM 


words per minute 




transistor 


VOM 


volt-ohm- 


WRMS 


watts RMS 


UPC 


universal product 




milliammeter 


Ws 


wattsecond 




code 


VOX 


voice-operated 


Z 


impedance 


UPS 


uninterruptible 




transmission 








power system 


VRMS 


volts RMS 







Abbreviations on Diagrams. Some foreign publica- 
tions, including Wireless World, shorten the abbre- 
viations for units of measure on diagrams. Thus, /x 
after a capacitor value represents ixF, n is nF, and p 
is pF. With resistor values, k is thousand ohms, M is 
megohms, and absence of a unit of measure is ohms. 
For a decimal value, the letter for the unit of measure 
is sometimes placed at the location of the decimal 
point. Thus, 3k3 is 3.3 kilohms or 3,300 ohms, 2M2 is 
2.2 megohms, 4/u7 is 4.7 /aF, 0/juI is 0.1 /xF, and 4n7 
is 4.7 nF. 



Semiconductor Symbols Used 



DIODES: 



Af ^, \K 



RECTIFIER 
DIODE 






1 ZENER 1 

DIODE 



fo 



TUNNEL 
DIODE 



THYRECTOR 
DIODE 



& R 



TRANSISTORS: 

NPN N-CHANNEL N-CHANNEL N-CHANNEL N-CHANNEL 

G2_ 



*C£ -@g [ ^s j& s 



VARACTOR 



N-CHANNEL 



PNPN 
DIODE 



N-CHANNEL 



E = EMITTER 
B = BASE 
C = COLLECTOR 
G = GATE 
A= ANODE 
K = CATHODE 
D= DRAIN 
S= SOURCE 
MT = MAIN TERMINAL 




PNP P-CHANNEL P-CHANNEL P-CHANNEL P-CHANNEL 

-B2 AihA-D 





S V^" B ' G 





BIPOLAR 



FET 



UJT 



MOSFET DUAL-GATE 

MOSFET 



DEPLETION- ENHANCEMENT- 
MODE MODE 
MOSFET MOSFET 



POWER CONTROL DEVICES: 

IA IA OA 




SCR 





Tg 

SUS 





TRIAC 



DIAC 



OPTOELECTRONIC DEVICES: 

LASCR 



$ W h 



LED OR 
LASER 



PHOTO 
DIODE 



PHOTO 
TRANSISTOR 



The commonest forms of the basic semiconductor 
symbols are shown here. Leads are identified where 
appropriate, for convenient reference. Minor varia- 
tions in symbols, particularly those from foreign 
sources, can be recognized by comparing with these 
symbols while noting positions and directions of solid 
arrows with respect to other symbol elements. 

Omission of the circle around a symbol has no 
significance. Arrows are sometimes drawn open in- 
stead of solid. Thicker lines and open rectangles in 
some symbols on diagrams have no significance. Ori- 
entation of symbols is unimportant; artists choose the 
position that is most convenient for making connec- 
tions to other parts of the circuit. Arrow lines outside 
optoelectronic symbols indicate the direction of light 
rays. 

On some European diagrams, the position of the 
letter k gives the location of the decimal point for a 
resistor value in kilohms. Thus, 2k2 is 2.2K or 2,200 
ohms. Similarly, a resistance of 1R5 is 1.5 ohms, 1M2 
is 1.2 megohms, and 3n3 is 3.3 nanofarads. 

Substitutions can often be made for semiconduc- 
tor and IG types specified on diagrams. Newer com- 
ponents, not available when the original source arti- 
cle was published, may actually improve the 
performance of a particular circuit. Electrical char- 



acteristics, terminal connections, and such critical rat- 
ings as voltage, current, frequency, and duty cycle, 
must of course be taken into account if experimenting 
without referring to substitution guides. 

Semiconductor, integrated-circuit, and tube sub- 
stitution guides can usually be purchased at elec- 
tronic parts supply stores. 

Not all circuits give power connections and pin 
locations for ICs, but this information can be obtained 
from manufacturer data sheets. Alternatively, brows- 
ing through other circuits may turn up another circuit 
on which the desired connections are shown for the 
same IC. 

When looking down at the top of an actual IC, 
numbering normally starts with 1 for the first pin 
counterclockwise from the notched or otherwise 
marked end and continues sequentially. The highest 
number is therefore next to the notch on the other side 
of the IC, as illustrated in the sketches below. (Actual 
positions of pins are rarely shown on schematic 
diagrams.) 





Addresses of Sources Used 



In the citation at the end of each abstract, the title of 
a magazine is set in italics. The title of a book or report 
is placed in quotes. Each source title is followed by 
the name of the publisher of the original material, 
plus city and state. Complete mailing addresses of all 
sources are given below, for the convenience of read- 
ers who want to write to the original publisher of a 
particular circuit. When writing, give the complete 
citation, exactly as in the abstract. 

Books can be ordered from their publishers, after 
first writing for prices of the books desired. Some 
electronics manufacturers also publish books and 
large reports for which charges are made. Many of the 
books cited as sources in this volume are also sold by 
bookstores and by electronics supply firms. Locations 
of these firms can be found in the YELLOW PAGES 
of telephone directories under headings such as 
"Electronic Equipment and Supplies" or "Television 
and Radio Supplies and Parts." 

Only a few magazines have back issues on hand 
for sale, but most magazines will make copies of a spe- 
cific article at a fixed charge per page or per article. 
When you write to a magazine publisher for prices of 
back issues or copies, give the complete citation, ex- 
actly as in the abstract. Include a stamped self-ad- 
dressed envelope to make a reply more convenient. 

If certain magazines consistently publish the 
types of circuits in which you are interested, use the 
addresses below to write for subscription rates. 

American Microsystems, Inc., 3800 Homestead Rd., Santa 

Clara, CA 95051 
Audio, 401 North Broad St., Philadelphia, PA 19108 
BYTE, 70 Main St., Peterborough, NH 03458 
Computer Design, 11 Goldsmith St., Littleton, MA 01460 
CQ, 14 Vanderventer Ave., Port Washington, L.I., NY 

11050 
Delco Electronics, 700 East Firmin, Kokomo, IN 46901 
Dialight Corp., 203 Harrison Place, Brooklyn, NY 11237 
EDN, 221 Columbus Ave., Boston, MA 02116 
Electronics, 1221 Avenue of the Americas, New York, NY 

10020 
Electronic Servicing, 9221 Quivira Rd., P.O. Box 12901, 

Overland Park, KS 66212 
Exar Integrated Systems, Inc., 750 Palomar Ave., Sunny- 
vale, CA 94086 
Ham Radio, Greenville, NH 03048 



Harris Semiconductor, Department 53-35, P.O. Box 883, 
Melbourne, FL 32901 

Hewlett-Packard, 1501 Page Mill Rd., Palo Alto, CA 94304 

Howard W. Sams & Co. Inc., 4300 West 62nd St., Indian- 
apolis, IN 46206 

IEEE Publications, 345 East 47th St., New York, NY 10017 

Instruments b- Control Systems, Chilton Way, Radnor, PA 
19089 

Kilobaud, Peterborough, NH 03458 

McGraw-Hill Book Co., 1221 Avenue of the Americas, New 
York, NY 10020 

Modern Electronics, 14 Vanderventer Ave., Port Washing- 
ton, NY 11050 

Motorola Semiconductor Products Inc., Box 20912, Phoe- 
nix, AZ 85036 

Mullard Limited, Mullard House, Torrington Place, Lon- 
don WC1E 7HD, England 

National Semiconductor Corp., 2900 Semiconductor Dr., 
Santa Clara, CA 95051 

Optical Electronics Inc., P.O. Box 11140, Tucson, AZ 85734 

Popular Science, 380 Madison Ave., New York, NY 10017 

Precision Monolithics Inc., 1500 Space Park Dr., Santa 
Clara, CA 95050 

QST, American Radio Relay League, 225 Main St., New- 
ington, CT 06111 

Radio Shack, 1100 One Tandy Center, Fort Worth, TX 
76102 

Raytheon Semiconductor, 350 Ellis St., Mountain View, CA 
94042 

RCA Solid State Division, Box 3200, Somerville, NJ 08876 

Howard W. Sams & Co. Inc., 4300 West 62nd St., Indian- 
apolis, IN 46206 

73 Magazine, Peterborough, NH 03458 

Siemens Corp., Components Group, 186 Wood Ave. South, 
Iselin, NJ 08830 

Signetics Corp., 811 East Arques Ave., Sunnyvale, CA 
94086 

Siliconix Inc., 2201 Laurelwood Rd., Santa Clara, CA 95054 

Sprague Electric Co., 479 Marshall St., North Adams, MA 
01247 

Teledyne Philbrick, Allied Drive at Route 128, Dedham, 
MA 02026 

Teledyne Semiconductor, 1300 Terra Bella Ave., Mountain 
View, CA 94040 

Texas Instruments Inc., P.O. Box 5012, Dallas, TX 75222 

TRW Power Semiconductors, 14520 Aviation Blvd., Lawn- 
dale, CA 90260 

Unitrode Corp., 580 Pleasant St., Watertown, MA 02172 

Wireless World, Dorset House, Stamford St., London SE1 
9LU, England 



MODERN 
ELECTRONIC 

CIRCUITS 
REFERENCE 

MANUAL 



CHAPTER 1 

Amplifier Circuits 



Includes general-purpose RF amplifiers covering various portions of spectrum 
from DC to 2.3 GHz at outputs up to 230 W, some with voltage-controlled 
gain, for pulses as well as video and other RF signals. See other chapters in 
book for RF amplifiers having specific applications. 



0.25-400 MHz CASCADE— Three hybrid mod- 
ules in cascade provide gain of 43.5 dB with flat- 

c ness of ±1 dB over frequency range. Circuit 

r}_ draws 44 mA from 12-VDC supply. Modules 1 

~ so S! and 2 are Motorola MWA110, and module 3 is 
MWA120. All capacitors are 0.018 pF. R1 and R2 
are IK, and R3 is 300 ohms. — "Wideband Hybrid 
Amplifiers," Motorola, Phoenix, AZ, 1978, DS 
5712. 




-MA 

10k 

HOT) 

OFFSET NULL 



GAIN: 75dB 
BW: 60kHz 

ALL RESISTANCES IN OHMS 

METAL-OXIDE FILM. 



CMOS/BIPOLAR VOLTAGE FOLLOWER— Com- 
bination of two 4007 CMOS gate packages and 
one CA3083 transistor package provides gain of 
about 75 dB as voltage-follower amplifier and 



bandwidth of 50 kHz. Slew rate is about 
30 V/jus, and settling time is 2 /us. Requires only 
single +15 V supply. Can be driven to within 1 
mV of ground. Interfaces well with single-sup- 



ply D/A converters.— B. Furlow, CMOS Gates In 
Linear Applications: The Results Are Surpris- 
ingly Good, EDN Magazine, March 5, 19*73, p 
42-48. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CAPACITIVE-LOAD EMITTER-FOLLOWER— 
Overcomes problem that develops with trailing 
edges of pulses when emitter-follower using 
NPN transistor is driving heavily capacitive 
load. Extra transistor is used to dump capacitor 
charge when emitter-follower stops conducting 
at trailing edge of input waveform. Pulse trail- 
ing edge thus tends to cut off Q, and saturate 
lower transistor so it discharges capacitor. Cir- 



cuit works equally well with pulses, square 
waves, and sine waves. Transistors need not be 
matched. Reverse polarity of supplies to use 
PNP transistors. Useful for driving long coax 
lines or logic from high-impedance source, 
without inversion. — H. L. Morgan, Emitter Fol- 
lower's Fall Time Is Independent of Load, EDN 
Magazine, Feb. 5, 1977, p 105. 




100 iiF 



BASIC FEEDBACK AMPUFIER— Combination of 
unipolar and bipolar transistors gives desirable 
amplifying features of each solid-state device'. 
Circuit can be optimized for RF or AF by adjust- 
ing coupling, feedback, and emitter bypass ca- 
pacitor values. Changes in feedback affect dis- 
tortion, frequency response, and gain stability. 
To optimize for RF, reduce capacitor sizes. For 



both AF and RF response, capacitors shown can 
be paralleled by small ceramic or Mylar units. If 
FET and bipolar are selected for high transcon- 
ductance and high gain-bandwidth product, 
overall voltage gain can be 20 or more for fre- 
quencies up to several megahertz. — I. M. Gott- 
lieb, A New Look at Solid-State Amplifiers, Ham 
Radio, Feb. 1976, p 16-19. 



200 pF T. 



0.1 ^H 



180 

-vWA- 



-© 




470 pF 



OUTPUT 
50s ! 



SfclOOOpF 



pF f r 1000 pF^; ~ 

0.2J«H"r' C0.22uH J_ J_ 



T, 4 TURNS 22 AWG TWISTED 
PAIR ON INDIANA GENERAL 
F62S9Q2 CORE 



V =sO-HI 



500pF5fe 



«F 
50V 



13 W at 160 MHz— Circuit uses Siliconix VMP-4 
power MOSFET to provide 11-dB gain with 26- 
V supply, or 14 dB with 36-V supply. Broadband 
design permits operation over wide range of 



:500pF 



frequencies up to as high as 600 MHz. — RF 
Power MOSFET Outputs 13 W at 160 MHz with 
High Gain, No Breakdown, EDN Magazine, June 
20, 1976, p 144-145. 




AC WITH IMMUNITY TO LARGE DC OFFSET— 
Designed to amplify from about 250 kHz down 
to low frequencies in presence of large DC input 
offsets. Main NE540L amplifier has gain of 101, 
while NE536T has DC gain of unity and forms 
part of low-pass network that applies DC input 
offset as common-mode voltage to inverting 
input of main amplifier. — A. Royston, Low Fre- 
quency AC Amplifier, Wireless World, May 
1976, p 80. 




M u.-»< 



SMALL-SIGNAL AMPLIFIER— Combines fea- 
tures of virtual-earth and high-input-impedance 
amplifiers economically for such applications as 
a record amplifier, and provides several times 
the gain of a virtual-earth amplifier alone. — D. 
Rawson-Harris, Small Signal Amplifier, Wire- 
less World, Feb. 1977, p 45. 



0.1 (iF 




INPUT A 10 "F 

750 mV p-p 

100 kHz 3 k 

INPUT B 1° pF 

100 mV p-p 

1 MHz 1.2 k ~ 

SUMMING/SCALING VIDEO— With Motorola 
MC1552G video amplifier connected as shown, 
summation of input signal currents is accom- 
plished at pin 4 through input resistors whose 
values are chosen to give desired scale factor. — 
"A Wide Band Monolithic Video Amplifier," Mo- 
torola, Phoenix, AZ, 1973, AN-404, p 9. 



AMPLIFIER CIRCUITS 




500 kHz TO 500 MHz — Two-stage general-pur- 
pose wideband small-signal amplifier provides 
nearly 14-dB gain at 150 MHz when inserted in 
50-ohm transmission line with no tuned circuits 
at input or output. Noise figure with optimum 
source resistance is about 3 dB at 150 MHz. Am- 
plifier is capacitively coupled common-emitter 
cascade. Capacitors make low-frequency gain 
begin dropping off below about 2 MHz. Increas- 
ing all capacitors to 0.01 pF will lower frequency 
response to about 200 kHz. — R. Rhea, General 
Purpose Wideband RF Amplifier, Ham Radio, 
April 1975, p 58-61. 



15 V 
O 0. 25 mA r, 

20uF i 

5K 



© 



0.1 



AF INPUT f R ])5 1 mo 




©: 



-O OUTPUT 1 



0.1 



Hf- 



0.1 



-O COMMON 



-O OUTPUT 2 



PARAPHASE PHASE INVERTER— Uses 180° 
phase difference between source and drain out- 
puts of Siliconix U183 FET to convert AF input 
to push-pull output without transformer. Volt- 
age gain in each half of circuit is about 0.8. Fre- 



quency response referred to 1 kHz is flat within 
3 dB from 50 Hz to 50 kHz, when using 1 -meg- 
ohm output load. — R. P. Turner, "FET Circuits," 
Howard W. Sams, Indianapolis, IN, 1977, 2nd 
Ed., p 29-30. 




BFxee 



230-W WATER-COOLED— Used to excite mag- 
netic specimens in frequency range of to 110 
kHz at outputs up to 12 A. Output stage uses 
two complementary pairs of emitter-followers 
connected so each pair forms half of bridge, 
using MJ4030 and MJ4033 Darlingtons 
mounted on liquid-cooled heatsinks. Article de- 



scribes cooling arrangement and circuit opera- 
tion in detail and gives suitable preamp circuit 
for driving inputs of BCY89 dual transistor. De- 
signed for 32-VDC supply, which connects to 
top and bottom horizontal buses on diagram. 
Feedback circuits are drawn in heavy lines. Re- 
sistors in series with Darlingtons (0R25, repre- 



senting 0.25 ohm) are wound from resistance 
wire since they must carry large currents. Out- 
put impedance of circuit is less than 0.5 ohm, 
for matching to low-resistance load. — I. L. Ste- 
fani and R. Perryman, Liquid-Cooled Power Am- 
plifier, Wireless World, Dec. 1974, p 505-507. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



t 



lOk (St* T»»t) 




5/8 

(16 mm) 




2304-MHz PREAMP— Narrow-band stage using 
Fairchild MT-2500 bipolar transistor gives gain 
of 6 to 9 dB and noise figure of 2.5 to 4.5 dB. 
Cavity resonators at both input and output give 
excellent frequency selectivity. Similar circuit 
can be used with Fairchild MT-4500, FMT-4005, 
or equivalent newer stripline-type transistors. 
RFC1 is 3 turns and RFC2 is 5 turns, air-wound 
with No. 26 enamel by using No. 52 drill as man- 
drel. Coupling strips on base and collector of 
transistor are 0.25-mm brass shim stock. Article 
gives construction and tune-up details, along 
with alternate design for HP-35821E and HP- 
35862E transistors using coupling loops. 10K 
pot is used only during tune-up. — N. J. Foot, 
Narrow-Band Solid-State 2304-MHz Preampli- 
fiers, Ham Radio, July 1974, p 6-11. 



MULTIPURPOSE MODULE— Flexible circuit 
using FET to drive bipolar transistor has -3 dB 
points at 100 Hz and 0.6 MHz. Components are 
noncritical and can be changed considerably in 
value to optimize gain, frequency response, 
power output, or power consumption. Load 
presented to FET is primarily input resistance of 
bipolar transistor, about 1000 ohms, which 
gives voltage gain of 4 for FET. — I. M. Gottlieb, 
A New Look at Solid-State Amplifiers, Ham 
Radio, Feb. 1976, p 16-19. 



/NO 




■oout 




X 



VG = 0.93X OPEN CKT 
0.5X INT. 5012 



K2N3704 
^» AV- 



RG-58U 



+6V 
35mA 



220 



T^> 



1 



6 r 



MAX OUT = 9 VP-P OPEN CKT 
2 VP-P INT. 50!! 



-6V 

35mA 



sion line or 50-ohm input of instruments such be boosted by using higher-frequency transis- 

as spectrum analyzer, video amplifier, or fre- tor. — M. J. Salvati, FET Probe Drives 50-Ohm 

IMPEDANCE CONVERTER — Used to match 10- quency counter. Voltage gain is exactly 0.5. Fre- Load, EDN Magazine, March 5, 1973, p 87 and 

megohm input impedance to 50-ohm transmis- quency response is from DC to 20 MHz and can 89. 



AMPLIFIER CIRCUITS 




FET-BIPOLAR SOURCE FOLLOWER— Used 
where source follower with high output-volt- 
age swing and voltage gain close to unity is re- 
quired. Circuit has constant-current bias supply. 
Combination of unipolar and bipolar transistors 
gives desirable amplifying features of each 
solid-state device.— I. M. Gottlieb, A New Look 
at Solid-State Amplifiers, Ham Radio. Feb. 1976, 
p 16-19. 



-AGCO » VW t 
0.002 «f~3 ^~ 0.002 V F 



[2IH41S Z - J~M 



1P& 



^X 



rr 



<^n 



AGC range 59 dB 
power gain 1 7 dB 



L1 • 0.07 «Hy center tap 

L2 - 0.07 juHy tap 1/4 up from ground 

200-MHz CASCODE—JFETs give low cross- JFET. Neutralization is not needed.— "FET Da- 
modulation, large signal-handling ability, and tabook," National Semiconductor, Santa Clara, 
AGC action controlled by biasing upper cascode CA, 1 977, p 6-26-6-36. 




Q,.Q 4 


2N3931 


R , 


3.09k, 1% 


Q 2 


2N3563 


R 2 ,R 7 


510,1% 


Q 3 


2N3773 


R 3 


100k, 1% 


D, 


1N759 


R 4 


1k, 1% 


c, 


100 pF 


R 5 .R 8 


5k, 1% 






R . 


10k, 5% 






R 9 


330, 5% 



120V 



HIGH-VOLTAGE BUFFER— Circuit shown for 
pA723 voltage regulator permits use as high- 
voltage and high-current buffer in linear appli- 
cations. Power dissipation of output transistor 
Q 3 is only limiting factor. I, is proportional to V, N , 



l 2 is proportional to I,, and output voltage V, is 
proportional to l 2 and V, N .— G. Niu, Single Op 
Amp Implements High-Voltage/Current Buffer, 
EDN Magazine, Oct. 5, 1977, p 96 and 98. 




5.6 k 
V AGC O— — AAA^ 

1.0 (jF 2 

e in O-j 1( — j-o 1^-^17 ' 



0.001 jjF 



.OuF 



\(r 



" — » — t t ■ « 



0.001 uF 

VIDEO AMPLIFIER— AGC capability of Motorola 
MC1590G makes it highly suitable for wideband 
video amplifier applications. Voltage gain is 
about 25 dB up to 50 MHz for 100-ohm load and 
45 dB up to 10 MHz for IK load. Several circuits 
can be cascaded to increase gain, using capa- 
citive coupling.— B. Trout, "A High Gain Inte- 
grated Circuit RF-IF Amplifier with Wide Range 
AGC," Motorola, Phoenix, AZ, 1975, AN-513, 
p9. 



INPUT O 



Vc=OV-GAIN-X100 
V -+10V-GAIN-X10 




O OUTPUT 



2N5462 



WIDEBAND VARIABLE GAIN— FET serves as 
gain-controlled device in feedback loop of Op- 
tical Electronics 9906 opamp. Resistive T net- 
work has SD201 MOS transistor as ground leg, 
with resistor values chosen so transistor is elec- 
trically close to summing junction, automati- 
cally limiting total signal voltage. Resulting ar- 
rangement of voltage-controlled feedback and 
compensation gives variable-gain amplifier 
with good linearity and constant wideband 
width for all gain levels.— "Wideband Variable 
Gain Amplifier," Optical Electronics, Tucson, 
AZ, Application Tip 10277. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



♦15 v°- 



'33M 



20 k 



-^ 



2N2060 



^ 



;R 2 
100 k^— 

trj° 5 2N222212) 



IN4I483L 



:!"3 :i 
? lk ? 



Qs 
2N2222 



«4 

Ilk 



>R 6 

" • tk 



-15 V o 

UNITY-GAIN VOLTAGE FOLLOWER— Mea- 
sured gain is 0.9997 V/V with an error of ±0.1% 
over ±1.5 V swing. Circuit has infinite input 
impedance and zero bias current. Addition of 



VOUT 



dashed components to simple voltage-follower 
design gives near-perfect performance. — C. An- 
dren. The Ideal Voltage Follower, EEE Maga- 
zine, Jan. 1971, p 63-64. 




CASCODE — Combination of unipolar and bi- 
polar transistors gives desirable amplifying fea- 
tures of each solid-state device. Ideal for use 
with tuned circuits in audio, video, IF, and RF 
applications. — I. M. Gottlieb, A New Look at 
Solid-State Amplifiers, Ham Radio, Feb. 1976, 
p 16-19. 



-I2 



HIGH-Z PREAMP — Provides up to 20 megohms 
of input impedance and has essentially flat re- 
sponse from 10 Hz to 220 MHz. Q3 serves as 
emitter resistor for Q2, and emitter-follower 04 
reduces loading. Input impedance is further in- 
creased by adding optional components shown 
in dashed lines. Transistors are 2N2188, 
SK300S, GE-9, or HEP-2.— Circuits, 73 Maga- 
zine, Feb. 1974, p 102. 




(9.0fol5.0v.) 



15 K 

4«- 
5% 



r©-»- 



5 resistor 
1 it desired 



>27K 
5% 



10 mf 
15« 

TANt. 



— WW— 



lOOfi 

i». 

5% 



^i>Cx (See text) 



( d.c. bias 
negative 
feedback ) 



ioon 

57. 



57. 



"I 1 ; 

T 



Q2 10 mf 

15v. 

TANT. 



r 



} 



10-dB GAIN AT 0.01-100 MHz— High-gain 
wideband untuned general-purpose amplifier 
uses Fairchild 2N5126 or equivalent transistors 
in direct-coupled circuit. Design is stable for 
both power supply and temperature variations. 
Gain is adjusted with R„ with maximum of 38 
to 44 dB and maximum output of about 1 V P-P. 
Will drive low-level transistor circuits having 
load of about 1000 ohms. If several amplifiers 
are used in series for higher gain, shielding is 
required. Applications include amplification of 
pulsed light signals detected by photodiode. C x 
can be 100-pF mica. — A. B. Hutchison, Jr., Gen- 
eral Purpose Wide Band Amplifier, CQ, May 
1972, p 22-23. 



AMPLIFIER CIRCUITS 




BIAS SUPPLY FOR CLASS AB— Two-transistor 
supply using PNP silicon transistor as amplified 
diode variable-voltage source gives improved- 
performance transistor RF power amplifier op- 
erating in class AB linear mode. Transistor types 
are not critical. Output impedance of bias 
source is about 1 ohm, and output voltage 
changes only up to 3 1 £% for ±2.5 V change in 
input voltage V cc - — C. P. Bartram, Bias Supply 
for R.F. Power Amplifiers, Wireless World, April 
1976, p 61. 



1-36 MHz DISTRIBUTED— Provides 18-dB gain 
over entire frequency range without use of spe- 
cial ferrite transformers. Gain contribution of 
each transistor, in phase with amplified wave as 
it passes down artificial transmission line, adds 
to that of other transistors. Capacitors marked 
with asterisks are low-inductance ceramic 
types such as Erie Redcap. Delay-line inductors 
L are 12 turns No. 24 closewound on 'A-inch di- 
ameter Lucfte rod, and U2 units are 7 turns. Can 
be used as preamp for frequency counter and as 
auxiliary for other test equipment. Article cov- 
ers construction, heatsinking of transistor, and 
testing.— H. Olson, Wide-Range Broadband 
Amplifier, Ham Radio, April 1974, p 40-44. 




SO-OHM/^JgL 



! ®-s^H- 



-^W\. i 



12.3 Vg 




C,= 300 pF {chipl 
L = 4.2 nH (adjust 



8 nH (adjust) 

130 pF (chip) 

750 pF (chip) 
22 /JF 



7 turns 

6.3 mm coil diameter 
o.8 mm wire diameter 
3 turns on ferrite bead 



0.68 MF 




118-136 MHz BROADBAND— Designed for low- 
level amplitude modulation system. 50-ohm 
line transformers are wound with copper ribbon 
on ferrite core to give 4: 1 ratio. Design and con- 
struction procedures are covered. Transistor is 
Motorola 2N6083, rated 30 W for 4-W input.— B. 
Becciolini, "Impedance Matching Networks Ap- 
plied to R-F Power Transistors," Motorola, 
Phoenix, AZ, 1974, AN-721, p 17. 



DIFFERENTIAL PAIR— Conventional differential 
amplifier circuit provides differential-mode gain 
of 96, common-mode input resistance of 500 
megohms, CMRR of 106 dB, and current-source 
output resistance greater than 1 gigohm. Article 
gives design equations. — R. C. Jaeger and G. A. 
Hellwarth, Differential Cascode Amplifier Offers 
Unique Advantages, EDN Magazine, June 5, 
1974, p 78 and 80. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



10k 



0.001 tiF 

°H 

R| N >100M ' 
C lN < 0.25 pF 



0.1 uF 



X 



2N5485 



10M 



-O 30V 



10k 



-I 2N3904 



-O OUTPUT 



R1 
"inO— WSr 



- give maximum possible reduction in input ca- 
HIGH INPUT IMPEDANCE— Simple JFET input pacitance. Used as unity-gain AC amplifier- 
circuit is operated as source follower with "FET Databook," National Semiconductor, 
bootstrapped gate bias resistor and drain to Santa Clara, CA, 1977, p 6-26-6-36. 




GAIN CONTROL 

VOLTAGE-CONTROLLED GAIN— 2N5457 FET 
acts as voltage-variable resistor between differ- 
ential input terminals of opamp. Resistance var- 
iation is linear with voltage over several de- 
cades of resistance, to give excellent electronic 
gain control. Values of resistors depend on 
opamp used. — "FET Databook," National Semi- 
conductor, Santa Clara, CA, 1977, p 6-26-6-36. 



P + 15V 



n (1+R2/R1)/R- 




6 -15V 



.1-10 ohms 



Typical ly 



100 W FOR DC TO 500 kHz— Circuit using Op- 
tical Electronics opamps has high input imped- 
ance, high gain capability, and 100-W output 
capacity without use of transformers, for high- 
fidelity audio circuits, cathode-ray deflection 
circuits, and servosystems. Output currents up 
to 10 A require heavy output wiring, large 
power-supply bypass capacity, and heavy com- 
mon ground point. Load is in feedback loop of 
opamp. Constant-current drive for load makes 
impedance matching to loudspeaker unneces- 
sary.— "A High Gain 100 Watt Amplifier," Op- 
tical Electronics, Tucson, AZ, Application Tip 
1020S. 



Point 



INPUT 



SIG /£~\ £RS-50fi 

GEN CV) 



0.1 uF 



v 12 

{(— — T o OUTPUT 



1K< l-i 



o.ooi mf|(- 



T 



T 

I 



O.luF 




o.ooi hf| 



VARIABLE CAPACITANCE (0.5-1. 0mF) ADJUSTMENT 
FOR EQUAL3-dB BANDWIDTH AT AMPLIFIER 
OUTPUTS, TERMINALS 10 AND 12. 



a33pF 
INPUT @ 1( — f ©- ^ 




20-MHz WIDEBAND— RCA CA3040 IC is con- 
nected for single-ended input and balanced out- 
put, with no resonant circuits. Gain is above 30 
dB over wide frequency range. — E. M. Noll, 



"Linear IC Principles, Experiments, and Proj- 
ects," Howard W. Sams, Indianapolis, IN, 1974, 
p 162-163 and 168. 



j-VW 



20-dB VIDEO — Simple circuit having gain of 20 
dB provides 3-dB bandwidth of 20 MHz for 
CA3100 bipolar MOS opamp. Total noise re- 
ferred to input is only 35 juVRMS. — "Circuit 
Ideas for RCA Linear ICs," RCA Solid State Di- 
vision, Somerville, NJ, 1977, p 12. 



AMPLIFIER CIRCUITS 



I 




PULSE 
GENERATOR 

(SN74123) 




CONSTANT OUTPUT IMPEDANCE— Pulse out- 
put stage gives output range from millivolts to 
10 V P-P across 50 ohms while optimizing wave- 
form characteristics of output pulse. With 



2N2904 output transistors, circuit delivers 200 
mA with 20-ms rise and fall times.— W. A. Palm, 
Pulse Amplifier Varies Amplitude, EDN Maga- 
zine, Aug. 5, 1978, p 76. 



3dB BANDWIDTH =15 MHi 
CLG'20dB 



^t_0.33 



±- 0.33,iF . 



J^^f 4 



DELIVERS FOLLOWING PEAK 
VOLTAGES TO 500 LINE 

FREO. j Vp 



IMHi 
2MHi 
4MHl 
BMHl 



8V 
5V 
2v 

I V 




OUTPUT TO 
TERMINATED 

son 

TRANSMISSION 

LINE 



LI =9T AIRWOUND, 10 TP.I. 

COLLECTOR TAP AT CENTER. 
OUTPUT TAP AT 1-3/4 TURNS 

50-MHz POWER— Developed for use with 50- 
MHz microtransistor crystal oscillator, using ad- 
ditional GE microtransistor for boosting RF out- 
put to about 75 mW. Article covers construction 
with microcomponents and gives other micro- 
transistor circuits for low-power amateur radio 
use and possible bugging applications. — B. 
Hoisington, Introduction to "Microtransistors," 
73 Magazine, Oct. 1974, p 24-30. 



20-dB VIDEO LINE DRIVER— RCA CA3100 
wideband opamp and power transistor output 
stage together provide gain of 20 dB at video 
frequencies for driving 50-ohm line. Peak output 
voltage ranges from 8 V at 1 MHz to 1 V at 8 



MHz. Upper frequency limit for unity gain is 
about 38 MHz. — "Linear Integrated Circuits and 
MOS/FET's," RCA Solid State Division, Somer- 
ville, NJ, 1977, p 225-227. 




PREAMP FOR 0.5 Hz TO 2 MHz— Provides 1 1-dB 
gain over entire frequency range, with input 
impedance of 32 megohms. Q3 is GE-2 or HEP- 
52, and other transistors are SK3020 or HEP- 
53.— Circuits, 73 Magazine, Jan. 1974, p 125. 



VIDEO ATTENUATOR— FETs in T attenuator 
provide optimum dynamic linear range for at- 
tenuation of video signals with ganged 1 -meg- 
ohm pots. If complete turnoff is desired, atten- 
uation greater than 100 dB can be obtained at 
10 MHz by using appropriate RF construction to 
minimize leakage. ON resistance of transistor 
(between drain and source) is less than 30 
ohms. — "FET Databook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 6-26-6-36. 



10 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




r_n_. 



CLAMPED 



PULSE BASEUNE CLAMP— Provides accurate 
clamping of baseline level of fast positive-going 
digital pulses with constantly changing duty 
cycle when capacitively coupled into level-sen- 
sitive circuits. Uses HA-2535 opamp. Diode D a 
clamps negative output swing of opamp to 
about 0.3 V, preserving amplifier recovery time 
in preparation for clamping next input transi- 



tion. Pulse widths at input are less than 100 ns, 
with transition time under 15 ns and duty cycle 
ranging from 2 to 50%. Diodes are HP 2800 se- 
ries. For clamping sine or triangle AF waves, 
opamp can be 741. — D. L. Quick, Clamp Speeds 
Restoration of AC-Coupled Base Lines, BDN 
Magazine, Sept. 5, 1975, p 76. 



I D . 202 nA 



Hh 



68k? 7.5k > 



V CC - +18V 

o 

l c3 . 1.0 mA 



OUTPUT 

o 



Q1.j 
— W2N3819 



2N2222S2L 



202 pA, 






.«E1 

■4.7k 



1.5k 



20k 1% 




POLARITY-IGNORING VOLTAGE FOLLOWER— 
Absolute-value circuit is basically voltage fol- 
lower A whose input is positive regardless of 
polarity of V IN . With positive input, inverting 
amplifier A,, is disconnected by D,. With nega- 
tive input, inverting amplifier applies positive 



input to voltage follower through D,. Output 
voltage is thus absolute value of input volt- 
age. — R. J. Wincentsen, Absolute Value Circuit 
Uses Only Five Parts, BDN Magazine, Nov. 1, 
1972, p 44. 




RF DIFFERENTIAL AMPLIFIER— Uses RCA 
CA3028A linear IC to provide power gain of 
about 32 dB at frequencies up to about 120 MHz. 
Values of tuned circuits depend on frequency 



Ot9V 



used. Unmarked resistors are on IC. — D. 
DeMaw, Understanding Linear ICs, QST, Feb. 
1977, p 19-23. 



STABILIZED BIAS— Simple voltage-feedback 
loop stabilizes bias on direct-coupled FET and 
bipolar transistor stages. Arrangement uses 
constant-current source Q2 to maintain stable 
bias voltage on base of Q3. By choosing proper 
resistor values, DC voltage feedback from emit- 
ter of bipolar is made to control constant-cur- 
rent value. Any change in drain current pro- 
duces opposite change in constant-current 
value, for stabilizing bipolar. Article gives de- 
sign equation. — H. T. Russell, DC Feedback Sta- 
bilizes Bias on FET/Bipolar Pair, EDN Magazine, 
Nov. 15, 1970, p 51. 



VinO— • ► 




VOUT 



R2 
v OUT s ^ V IN 

HIGH-IMPEDANCE VIDEO— Compound series- 
feedback circuit using FET at input provides 
high input impedance and stable wideband gain 
for general-purpose video amplifier applica- 
tions. — "FET Databook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 6-26-6-36. 



AMPLIFIER CIRCUITS 



11 



(PP9) 
battery 




,250u, _ »250u. 



■p^auu. m 



,250 m. 



i250u 



output 



,250u. 



2.5-MHz BANDWIDTH LOW-NOISE— Paralleled 
transistors meet noise requirements of appli- 
cations such as hot-wire anemometry for mea- 
suring gas flow and temperature, wherein typ- 
ical signal voltages are as small as 1 /tV peak 
over frequency range of 100 Hz to 200 kHz. Two 
feedback paths are used, one to provide low DC 
gain and stabilize bias voltages and the other 
for independent adjustment of AC gain. Design 
bandwidth is 7 Hz to 2.5 MHz.— J. A. Grocock, 
Low-Noise Wideband Amplifier, Wireless 
World, March 1975, p 117-118. 



50-dB BROADBAND VIDEO— RCA CA3018 four- 
transistor array is connected as two pairs of 
common-emitter emitter-follower combina- 
tions, with two feedback loops providing high 
DC stability. One path goes from emitter of 03 
back to input, and other goes from collector of 
Q4 to collector of Q1. Values of CI, C2, and C3 
give low-frequency cutoff (3 dB down) of 800 Hz. 
Upper cutoff is 32 MHz.— E. M. Noll, "Linear IC 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 1974, p 165-168 and 
174. 




ciStimf 



° v 0UT 



vs 

(fy\ 50-OHM 
S^ SOURCE 



?6V 

1 




0.47 uF 
^100 pF 



— M 

0.47 uF 



96V 

IrJi 

CA3000 




" AGC 
VOLTAGE 

WV- 



8000Q £8000fi 



v 0UT 



> 1000 



4.7 uF 



RC-COUPLED DIFFERENTIAL— Input signal is 
applied to base of first differential amplifier and 
push-pull output is obtained from pins 8 and 10 
for transfer to inputs of second IC. Feedback is 
transferred through RC combination back to pin 
6 of first IC. Gain is varied with AGC voltage ap- 
plied to pin 2 of first IC. Gain is over 60 dB with 
flat response from 100 Hz to 100 kHz. — E. M. 
Noll, "Linear IC Principles, Experiments, and 
Projects," Howard W. Sams, Indianapolis, IN, 
1974, p 89-91. 



12 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



50 (5)— 




BOTTOM V/EW 
OUTPUT — (oo oj — INPUT ^ 




<? R L0UT 



40-265 MHz VMOS— Wideband power amplifier 
using Siliconix Mospower FET in negative-feed- 
back circuit has flat gain within 0.5 dB over en- 
tire operational range of 40 to 265 MHz. Use 6 
to 8 turns of No. 30 on %-W 1-megohm resistor 
for L1 (not commercially molded choke). T1 is 



4 turns No. 22 twisted-pair on Indiana General 
F625-9Q2 toroid core. Avoid static charges until 
transistor is soldered into circuit.— E. Oxner, 
Mospower FET as a Broadband Amplifier, Ham 
Radio, Dec. 1976, p 32-35. 



FET CASCODE VIDEO— Use of 2N5485 FETs 
gives very low input loading, with feedback re- 
duced almost to zero. Bandwidth of amplifier is 
limited only by load resistance and capaci- 
tance. — "FET Databook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 6-26-6-36. 



+12Vdc 



15CVF 



SIGNAL OUT 
O 




CONTROL VOLTAGE 
04.5V 



ALL TRANSISTORS ARE 2N5172 
ALL DIODES ARE 1N4148 



150«F 



-10Vdc 



70-dB VOLTAGE-CONTROLLED GAIN— Ampli- 
fier Q, uses current source Q* as emitter resistor 
to provide correct current bias for class A op- 
eration. Coupling through 150-/*F capacitor to 
silicon diode string D,-D„ provides variable re- 
sistance needed to achieve variable gain. Sim- 
ple differential amplifier Q 3 -Q, adjusts forward 
bias of diodes to change their forward resis- 
tance. Increasing positive control voltage from 
to 4.5 V changes voltage gain from -74 dBm 
to about -4 dBm with respect to 0-dBm input 
signal. — N. A. Steiner, Voltage-Controlled Am- 
plifier Covers 70 dB Range, EDN Magazine, 
March 6, 1975, p 72 and 74. 




C,„, R,„, 

10uF 51k 

"»— 7,— Wv-, 

10uF 51k 

>_)|_^VV- 



HIGH 2 
OUTPUT 



SUMMING AMPLIFIER— Uses RCA CA3018 
four-transistor array as current-mirror triad 
with low-impedance buffered output, to serve 
as high-performance summing amplifier. Mea- 
sured harmonic distortion is less than 1% at 
voltage gains up to 50 and with output swing 
of 10 V P-P. High output impedance of 51 kil- 
ohms can be buffered by Q 2 connected as emit- 
ter-follower. — W. G. Jung, Monolithic-Triad 
Current Summer, EDNIEBE Magazine, July 1, 
1971, p 52. 



LOW Z 
OUTPUT 



AMPLIFIER CIRCUITS 



13 



+ 1.3V 
INPUT O 1(- 




MODULE INPUT 



O OUTPUT 



O V B - +6.8 V 




r~* 



168-MHz BANDPASS — Gain stage provides 
gain of 6 dB from 162 to 174 MHz. Skirt slope 
immediately outside passband decreases at 80 
db/MHz. Uses dispersive-design surface-acous- 
tic-wave bandpass filter with 168-MHz center 
frequency, 7% bandwidth, and extremely steep 
skirt response. Parallel inductor at collector ter- 
minal matches capacitance of acoustic-wave 
device, and tapped inductor matches output 
terminal of filter to 50 ohms. Used in spread- 
spectrum communication receiver. Article cov- 
ers design and construction of filter on quartz 
substrate. — T. F. Cheek, Jr., R. M. Hays, Jr., and 
C. S. Hartmann, A Wide-Band Low-Shape-Fac- 
tor Amplifier Module Using an Acoustic Sur- 
face-Wave Bandpass Filter, IEEE Journal of 
Solid-State Circuits, Feb. 1973, p 66-70. 



CASCODE RF/IF— Uses half of Signetics 511 
transistor array to provide voltage gain of about 
10 over bandwidth of 2 MHz with output volt- 
age swing of 12 V P-P. Design procedure is 
given. Circuit provides excellent isolation be- 
tween input and output. — "Signetics Analog 
Data Manual," Signetics, Sunnyvale, CA, 1977, 
p 746-747. 



F = 60 MHz 
BW = 0.5 MHz 
POWER GAIN* 30 dB 
P 0UT -1.8mW 
2 L = 52 



18 pF 
Z| N = 50S1 o II •> 




O V + = 6 V 



O ZOUT = 5° 1! 






-Ov* 



VinO- 



I 2NS48S 
t » 1 | 



-Ov 0UT 



10M 



60-MHz NARROW-BAND— Signetics NE510/51 1 
transistor array provides bandwidth of 0.5 MHz 
f or 3 dB down and noise figure of 7 dB for power 
gain of 30 dB. Maximum output swing across 50 



ohms is 300 mVRMS. Circuit is easily tuned. — 
"Signetics Analog Data Manual," Signetics, 
Sunnyvale, CA, 1977, p 749. 



WIDEBAND BUFFER — Low input capacitance of 
2N5485 FET makes compound series-feedback 
buffer serve as wideband unity-gain amplifier 
having high input impedance. — "FET Data- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 6-26-6-36. 



1* 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



INPUT FROM 
50-OHM SIGNAL 
GENERATOR 




9+6VDC 



O.lMF 



-o OUTPUT 



BNC COUPLED OUTPUT 
IS APPROXIMATELY 
EQUAL TO 8.5 pF LOAD 



0.1 mF 



* FERRITE BEADS ■ FERROXCUBE 
No. 56-590-65B-3B.OR EQUIV. 



80 MHz WITH INPUT PEAKING— Response of 
CA3040 video IC is extended beyond 80 MHz in 
simple circuit that includes adjustable input 
peaking coil. Response is flat within 3 dB to well 
below 1 MHz, for gain of about 32 dB. — E. M. 
Noll, "Linear IC Principles, Experiments, and 
Projects," Howard W. Sams, Indianapolis, IN, 
1974, p 163 and 169. 




10-MHz WITH 30-dB GAIN— CA3000 IC is oper- 
ated as RF amplifier with single-ended input 
and output. With appropriate tuned circuits, 
amplifier performs well up to 30 MHz. — E. M. 
Noll, "Linear IC Principles, Experiments, and 
Projects," Howard W. Sams, Indianapolis, IN, 
1974, p 91-92. 




DIFFERENTIAL CASCODE— Direct-coupled 

single-stage amplifier with differential input 
and output can be used in one or more stages 
of high-performance amplifiers. Bipolar-JFET 
cascode arrangement offers significant increase 
in common-mode input resistance and CMRR as 
compared to conventional differential pair, with 
little or no degradation of other performance 
parameters. Differential-mode gain is 1 16, com- 
mon-mode input resistance is greater than 100 
gigohms, CMRR is greater than 160 dB, and cur- 
rent-source output resistance is greater than 1 
gigohm. Article gives design equations. — R. C. 
Jaeger and G. A. Hellwarth, Differential Cascode 
Amplifier Offers Unique Advantages, EDN Mag- 
azine, June 5, 1974, p 78 and 80. 



C, 

HI 

3pf R, R* 

Wr J W- 




-OE,, 



1 100(1 



Ri?33kfl 



150 pF 



Trim (of E = E» (a E lWW -. 
* * Trim lor minimum THO (a E«, lm „>. 

VOLTAGE-CONTROLLED OPAMP— CA3080A 
operational transconductance amplifier uses 
bridge to provide automatic temperature com- 
pensation of gain that is controlled by voltage 
between and + 10 V applied to opamp A 3 . With 
values shown, input and output signal-handling 
range is ± 10 V. Once balanced, circuit provides 
linear gain control up to four decades. — W. G. 
Jung, "IC Op-Amp Cookbook," Howard W. 
Sams, Indianapolis, IN, 1974, p 455-456. 



CHAPTER 2 

Antenna Circuits 



Includes circuits for measuring and adjusting VSWR, field strength, earth 
conductivity for grounds, and impedance, as well as antenna motor controls, 
radio direction finders, sferics receiver, active antennas, RF attenuators, 
remote antenna switching systems, RF magnetometer, and far-field signal 
sources for tuning beam antennas. See also Receiver, Transceiver, and 
Transmitter chapters. 



A 3 



'~r->rr^ T 2 



270 
-^VW-O+VDD 




270 
-WV-O+Vdo 



o-^sc^wv-o 

(A) 



CR1 , CR2 - Light-emitting diode, Motorola 

type MLED600 or equiv. 
CR3-CR6, incl. - Silicon signal diode, 1N914 

or equiv. 
K3-K5, incl. - Switching relay, 12 V dc. 



1200 ohms, 10 mA; contact rating 1 A; 

125 V ac; Radio Shack 275-003 or equiv. 
Q1-Q5, incl. - Silicon npn transistor, 2N3904 

or equiv. 
RV1 - Varistor, GE 750 or equiv. 



U1 , U2, U5 - CMOS quad NAND-gate IC 

RCA CD-4011A or equiv. 
U3 - CMOS quad NOR-gate IC, RCA CD- 

4001 A, or equiv. 
U4 — Timer IC, 555 or equiv. 



DELAYED BRAKE-Protects antenna rotator on in other direction. For about 3-s delay in timer rotor system. Article covers construction and 

high tower from damage by delaying brake ac- U4, use 22 megohms for R and 1 „F for C in- installation, including modifications needed in 

tton automatically after rotation and by disa- stead of values shown. RV1 is commonly listed control unit.-A. B. White. A Delayed Brake Re- 

bling direction-selector switches so antenna as V150LA20A by GE. S3-S5 are original brake lease for the Ham-ll, QST, Aug 1977 p 14-16 

system coasts to stop before rotation can begin release and direction switches in CDE Ham-ll 



15 



16 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



LADDER ATTENUATOR— Inserted in 
with receiving antenna to provide 5 steps of at- 
tenuation for comparing performance of anten- 
nas or preamps. Resistors are Vi-W composition 
with 5% tolerance. — D. DeMaw, What Does My 
S-Meter Tell Me?, QST, June 1977, p 40-42. 




TWO-ROTATOR CONTROL— Low-cost Alliance 
C-225 TV antenna rotator and Alliance K22A ro- 
tator with control box are used with single tran- 
sistorized-bridge control circuit. Rotators op- 
erate in tandem on same shaft to provide 



double torque for handling medium-size 20- 
meter amateur radio antennas. One arm of 
bridge is 520-ohm wirewound pot in which 
wiper position is proportional to heading. Arti- 



cle covers wiring and bench-testing of rota- 
tors. — F. E. Gehrke, Antenna Rotator for Me- 
dium-Sized Beams, Ham Radio, May 1976, p 48- 
51. 



ANTENNA CIRCUITS 



17 



3)13 
(see text ) 



U-r 1 




220k / 470k 




4M7 



-O0V 



-<^> 




^^- 





300mA 




100n "^ » 500n 

ANTENNA ROTATOR— Two-opamp Wheat- tenna. Circuit will operate with supply ranging +" " + I 

stone bridge provides positive and negative from 15 to 28 VDC. Offset null controls for 5 * ! ^ 

error signals to give proportional control for 24- opamps use 10K pots. Article describes opera- Terfer, An Aerial Rotator Servo, Wireless World, 
VDC motor used for remote positioning of an- tion and adjustment of circuit in detail. — D. J. April 1975, p 177-181. 




C8 




I. 


12 


r h 


A 

2 


J CLK 

« 0,7 „ 

vcc 

Clr g 




I/2SN54H 



IC 12 8 IC 13 

PIN NO. 14* *5VCC 
PIN NO.7-GN0 



DVM FOR SWR— Converts voltage output from Requires regulated 5-VDC logic supply at 1 A for racy of digital reading is better than 0.1% over 

analog computer to drive for 3-digit LED display digital display, along with ±15 V supplies for 0-8 V range.— T. Mayhugh, The Automatic SWR 

of standing-wave ratio. Circuit uses Precision logic. Article gives alignment procedure. Accu- Computer, 73 Magazine, Dec. 1974, p 86-87. 
Monolithics D/A converter A1MDAC-100CC-Q1. 



18 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



.l"(2,3cm)0AP 
'IN SHIELD 



RG-59/U COAX 





EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS ( JlF I ; 
OTHERS ARE IN PICOFARADS I pF OR JiJlF); 
RESISTANCES ARE IN OHMS ; 
k-1000, M-IOOO OOO. 



SIG. 
"MAX. 



NULL 
(C) 



SHIELD BOX 
(WEATHERPROOF) 



160-METER LOOP-PREAMP— Shielded 5-foot 
square loop and single preamp pull signals out 
of noise when propagation conditions make 
other antennas unsatisfactory. Operating volt- 
age is supplied through coax feeder. R1 isolates 
signal energy from ground, and C2 keeps DC 
voltage out of receiver input. Nulls are off broad 
side of loop. — B. Boothe, Weak-Signal Recep- 
tion on 160 — Some Antenna Notes, QST, June 
1977, p 35-39. 



TO 
Rl 



FAR-FIELD TRANSMITTER— Provides far-field 
signal source for tuning Yagi and other beam 
antennas used on amateur radio frequencies. 
Q1 is Pierce oscillator operating in fundamental 
mode of 7.06-MHz crystal to permit field- 
strength measurements at 14.12, 21.18, and 
28.24 MHz for 20-, 15-, and 10-meter bands. An- 
tenna uses two 5-foot lengths of wire con- 
nected as dipole. T1 is Amidon core T50-2 with 
22 turns on primary and 20 turns center-tapped 
on secondary. T2 is same core with 22-turn pri- 
mary and 5-turn secondary. — G. Hinkle, Closed 
Loop Antenna Tuning, 73 Magazine, May 1976, 
p 32-33. 



R2 

ieo 

+ I2V a — WN<- 



Xfc 



FREQUENCY DOUBLER 



AMPLIFIER 





VSWR METER— Simple, easily transported 
VSWR meter consists of high-gain amplifier, 
narrow-bandwidth (100-Hz) selective amplifier 
tuned to 1000 Hz, and variable-gain output am- 
plifier driving low-cost VU meter. Ideal for null- 
ing-type VSWR measurements. Draws only 
about 6 mA from 9-V transistor battery. Closing 
S1 increases gain about 100 times for low-level 
readings. Rl sets (JIB to 1000 Hz, while R2 sets 
reference on VU meter. — J. Reisert, Matching 
Techniques for VHF/UHF Antennas, Ham Radio, 
July 1976, p 50-56. 



+ 9 TO +20V 



ANTENNA CIRCUITS 



19 



S3 Ja 

no test To Load 
under test 




Q,-Qi-RCA 40245. 

Si — 2 pole 6 position subminiature rotary 

switch. (Cenferlab PA-2005). 
S2— S.p.d.t. slide switch. 
S3— S.p.s.t. slide switch. 
T,— PH.: 1 1 t. #36 e. Sec.: 3 t. #36 e. on 

Indiana General CF-101 Q2 toroid. 
T 2 -Pri.: 16 t. #36 e. Sec: 4 t. #36 e. Same 

core as T,. 



T 3 — Pri.: 20 t. #36 e. Sec: 5 t. #36 e. Same 

core as Ti. 
Y|, Y i( Y 3 — Overtone crystals for 10, 15 and 

20 meter bands respectively. HC-6U 

holders. 
Y4, Y s — 40 and 80 meter crystals respectively 

in HC-6U holders. 



SELF-EXCITED SWR BRIDGE— Portable bridge 
has built-in signal sources for each band from 
80 through 10 meters, for tuning antenna on 
tower before transmission line is connected. 
Oscillators are crystal controlled at desired an- 
tenna tune-up frequencies. Separate oscillators 
for each band simplify switching problems, so 
only supply voltage from J, and oscillator out- 
puts to meter circuit need be switched. Current 
drain from 9-V battery is maximum of 12 mA. 
R 17 and R, e should be closely matched, while R, s 
and R 2D should have 5% tolerance. — T. P. Hulick, 
An S.W.R. Bridge with a Built-in 80 Through 10 
Meter Signal Source, CO. June 1971, p 64-66, 
68, and 99. 



POWER SUPPLr DECOUPLING 
22* H 
15V INO — t-^^-f-o.|5« OUT 



-"LEVEL" 




'■'I ?Z.7Kf Z.7K 
"7 { */yv<>R32 






SWR COMPUTER— Automatically computes (V FIN ) and reverse (V RIN ) voltages as convention- critical resistors during alignment.— T. May- 
standing-wave ratio in 50-ohm coax feeding an- ally measured for SWR checks. Requires regu- hugh, A Digital SWR Computerl, 73 Magazine, 
tenna and delivers analog voltage for driving lated ±15 VDC supply at 40 mA. Article gives Nov. 1974, p 80-82, 84, and 86. 
meter or digital display. Inputs are forward construction details and covers adjustment of 



20 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




C1, C2 - 39- and 10-pF silver micas in 

parallel. 
C3 — 5-pF silver mica. 
C4 — 250-pF straight-line-wavelength 

variable (Hammarlund MC-250M). 
C5 — 365-pF miniature variable 

(Archer-Allied 695-1000). 
CR1 — Germanium diode. 
J1 , J2, J4, J5 — Coaxial receptacle. 
load J3 _ Phono jack. 

OR L/C . .. i c * 

network L1 - 15 turns 

close-wound on 

form (purple slug). 
L2 - 30 turns like L1 . 
L3 — 63 turns 

scramble-wound. 
SI — 2-pole 3-position wafer switch. 



No. 24 enamel 
Miller 66A022-6 



ike LI, 



but 



5-STEP ATTENUATOR— Applications include 
comparing performance of various receiving an- 
tennas and measuring gain of preamp used 
ahead of receiver. Dashed lines represent re- 
quired shield partitions. All resistors are 1 A-W 
composition with 5% tolerance. — D. DeMaw, 
What Does My S-Meter Tell Me?, QST, June 
1977, p 40-42. 



RF BRIDGE FOR COAX— Simplifies adjustment 
of vertical antenna for 40, 80, and 160 meters. 
S1 in add-on LC unit switches coil for desired 
band. Values of C1-C4 and standard resistor R1 
give range of 10 to 150 ohms for measurement 
of radiation resistance. Meter can be from SO to 
200 juA full scale if 500 mW of power is available 
as signal source. For shorter-wavelength bands, 
change resistance in parallel with J1 to 5600 
ohms and omit C6. LI for 10 meters should then 
have 3 1 A turns No. 18 spaced to occupy 'A inch 
on Miller 4200 coil form. L2 (15 meters) is 6 turns 
No. 16 enamel closewound on similar form. L3 
(20 meters) is 11 turns No. 14 enamel on Miller 
66A022-6 form. — J. Sevick, Simple RF Bridges, 
QST, April 1975, p 1 1-16 and 41. 



ATTENUATOR 



20dB 20dB 

r 1 



VO\6 | J2 

V\ S5 | OUTPUT 




RF AMPLIFIER 




EXCEPT AS INOICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS ( JiF I ; 
OTHERS ARE IN PICOFARADS I PF OR JiJlFI; 
RESISTANCES ARE IN OHMS ', 
kHCOO, M-1000 000. 



OSCILLATOR 



BUFFER 





DETECTOR 



^pf^] 



;R16 

i'20l< Q5 




01 J— -. 

... "-©-. 



>R<8 
»47k 



80-METER DIRECT-CONVERSION— Portable re- 
ceiver with directional ferrod antenna and ver- 
tical sense antenna was developed for radio 
foxhunting at 1975 Boy Scout World Jamboree 
in Norway, in competitions for locating four 
low-power crystal-controlled transmitters hid- 
den along 4-km course. Varactor-tuned oscilla- 



tor provides 20-kHz tuning range with R9, ade- 
quate for the frequency used — 3.566, 3.585, 
3.635, or 3.680 MHz. T1 is subminiature auto- 
transformer with 8-ohm and 2000-ohm sec- 
tions, for 8-ohm headphones. For high-imped- 
ance headphones, connect headphone jack J1 



to lug 9 of T1. ON/OFF switch is not needed. LI 
is 22 turns No. 28 enamel wound over two 10 
x 95 mm ferrite rods taped together. Q1-Q6 are 
NPN high-frequency small-signal transistors. — 
N. K. Holter, Radio Foxhunting in Europe, QST, 
Nov. 1976, p 43-46. 



ANTENNA CIRCUITS 



21 



CR1 to CR4, 
incl. — Silicon 
diode, 1 A, 
50PRV. 

K2 - Dpdt 
relay, 6-V dc 
(Potter and 
Brumf ield 
KA 11 DG). 



K1, 



r 




TO XMTR 9RCVR. 



RFC1, RFC2 _ 
112 turns of 
No. 26 
enam. wire 
on 1 ,2-ohm 
2 -watt re- 
sistor. 



LI.L2 > SEE TEXT 
Z = LENGTH TO FIT MINIBOX 
,C2 = 500 pF BUTTON 



6 

SND. 



EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS I pf ) ; 
OTHERS ARE IN PICOFARADS { PF OR iliiF); 
RESISTANCES 'ARE IN OHMS ; 
k = I 000. M=IOOO 000. 




3-ANTENNA REMOTE SWITCHING— Single RF 
feed line serves for feeding transmitter power 
to tower and selecting desired one of three an- 
tennas. With SI at a, neither K1 nor K2 is ener- 
gized. RF energy then passes through cable to 
antenna terminals a' and GND. In position b. 



positive half-waves from 12-VAC supply oper- 
ate relay K1 through CR1 and CR3, so antenna 
b' is energized. With SI at c, K2 is energized 
through CR4 and CR2forfeeding c'.— U. H. Lam- 
mers, A Remote Antenna Switch, QST, Aug. 
1974, p 41-43. 



SWR TO 500 MHz— Permits measuring stand- 
ing-wave ratio well above limits of many inex- 
pensive indicators. For transmitters up to 2 W, 
coupling loop L1-L2 can be about 1 inch long. 
For high-power transmitters, loop length can be 
reduced to about '» inch.— W. E. Parker, UHF 
SWR Indicator, 73 Magazine, June 1977, p 68- 
70. 



HOIST MOTOR 
1 




A1 — Three-cup anemometer (Taylor Instrument 

Corp. No. 14077Q). 
CR2-CR5, incl. - Silicon diode 100 PRV 1 A 
CR6, CR7 - 1N69. 
F1 - 3.2 A, Slo-Blo. 
DS1 — Neon indicator. 

WIND-ACTIVATED CONTROL— Anemometer 
feeding meter relay energizes control relay for 
antenna-tower hoist motor, to lower tower au- 
tomatically when wind exceeds preset safe 



K1. K2 - Dpdt, 10-A, 124-V contacts, 320-ohm 
coil (Automatic Electric PG 24809-B11.) 

K3 - Meter relay, 100 «A (Weston No. S46707). 

R2. R3 - Approximately 12,000 ohm, 1-watt; see 
text. 

S1 - Spst (JBT No. MS-35058-22). 

S2, S6 - Dpdt center off (JBT. No. 35059-27). 

S3 - Dpdt normally off (JBT No. MS-35059-30). 

speed and raise K again when wind drops well 
below danger level. When only K1 is energized, 
motor rotates in tower-lowering direction. 
When K1 and motor-reversing relay K2 are both 



REMOTE CONTROL 



54 - Part of K3. 

55 -Spdt, bottom limit switch (Microswitch No. 

B2E6-2RN). 
T1 - 1 17-V primary, 24-v secondary, 300 mA 
U1 — Bridge rectifier assembly (Bradley Labs 
No. C014E4F). 

energized, motor reverses and raises tower. — 
J. Bernstein, The Tower-Guard System, QST, 
Dec. 1974, p 25-28. 



22 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



I MEG 



Jl 

ant' 







C1 - 140-pF variable. 

C2 - 15-pF variable. 

CR1.CR2 - 1N914orequiv. 

L1 — 34 turns No. 24 enam. wound on an 

Amidon T-68-2 core, tapped 4 turns from 

ground end. 
L2 — 12 turns No. 24 enam. wound on T-68-2 

core. 
L3 — 2 turns No. 24 wound at ground end of L2. 
L4 — 1 turn No. 26 enam. wound at ground end of 

L5. 

LINEAR FIELD-STRENGTH METER— Has suffi- 
cient sensitivity for checking antenna patterns 
and gain while positioned many wavelengths 
from antenna. Can be used remotely by con- 
necting external meter at J2. L1 is tuned by CI 
for 80 or 40 meters. For 20, 15, or 10 meters, L2 
is switched in parallel with LI. L5 and C2 cover 



L5 - 12 turns No. 26 enam. wound on T-25-12 

core. 
L6 - 1 turn No. 26 enam. 

L7 — 1 turn No. 18 enam. wound on T-25-12 core. 
M1 -50 or 100/UAdc. 
R2 — 10,000-ohm control, linear taper. 

51 — Rotary switch, 3 poles, 5 positions, 3 
sections. 

52 — Rotary switch, 1 pole, 4 positions. 

53 - Dpst Toggle. 
U1 - JHA741. 

about 40 to 60 MHz, while L7 and C2 cover 130 
to 180 MHz. Band-switched circuits avoid use of 
plug-in inductors. At most sensitive setting of 
S2, M1 will detect signals from pickup antenna 
as weak as 100 /uV. — L. McCoy, A Linear Field- 
Strength Meter, QST, Jan. 1973, p 18-20 and 35. 




DS1 — 100-watt light bulb. 

R1 — 14.6 ohms (5 watt). 

Probes — 5/8-inch dia (iron or copper); 

spacing, d = 18 inches; penetration depth, 

D = 12 inches. y. 

Earth conductivity = (21) x 

V2 

(millimhos/meter). 



EARTH CONDUCTIVITY— Simple AC measure- 
ment technique gives 25% accuracy, adequate 
for siting amateur radio antennas and designing 
radial ground systems. Measured values will 
range from 1 to 5 millimhos per meter for poor 
soil, 10-15 for average soil or fresh water, 100 
for very good soil, and 5000 for salt water. — J. 
Sevick, Short Ground-Radial Systems for Short 
Verticals, QST, April 1978, p 30-33. 



1. w 1 — t-nrm^ 




: %■ 



3X\ 



6 6 




6 6 

TO XMTR » RCVR 



, R2 R3> >R4 



FOUR-POSITION MOTOR SWITCH— Single RF 
feed line also carries DC for3-V permanent mag- 
net DC motor B1 atop antenna tower, driving S3 
and S4 for remote switching to antennas a, b, 
c, and d. Diagram shows switches set for feed 
to antenna a, with no drive applied to B1 since 
cam C has opened microswftch S5. CR5 and CR6 
are now connected in series with opposite po- 
larity, so neither positive nor negative half- 
waves from 12- VAC supply can drive motor. If 



S2 is closed, positive half-waves start B1. Once 
started, motor runs until cam opens S5; if S2 
has not yet been released, motor continues run- 
ning on positive and negative half-waves. Diode 
bridge CR1-CR4 makes motor rotate in only one 
direction for either drive polarity. If S2 is re- 
leased, before S5 opens, motor stops. 6-V 1-A 
lamp DS1 comes on dimly when S2 is closed 
and brightens when S5 closes. If S2 is released 



now, B1 drives to next position and stops. If S2 
is held down, switching continues. Meter Ml 
and CR7 identify position of switch. R1-R4, in 
range of IK to 10K, are chosen to give 1 A, % %, 
and full deflection of meter. Motor drives switch 
through 2860:1 reduction gears taken from 
alarm clock. All diodes are 50-PIV 1-A silicon 
such as 1N4001. — U. H. Lammers, A Remote 
Antenna Switch, QST, Aug. 1974, p 41-43. 



ANTENNA CIRCUITS 



23 



I.8-2.0MH2 
CIA C1B 



16' (406mm} 
SENSE ANTENNA 




EXCEPT AS INDICATED, OECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS I JlF ) ; 
OTHERS ARE IN PICOFARADS ( pF OR JJJlF); 
RESISTANCES ARE IN OHMS ', 
k'1000, M'1000 000. 



160-METER PREAMP WITH FERRITE LOOP— 
Ferrite-rod antenna is combined with 16-inch 
wire rod to give cardioid radiation pattern for 
low-noise 160-meter antenna system. Preamp 
using MPF102 FETs has gain of 25 dB. LI is 48 
turns No. 14 enamel spread to 4.5 inches on 0.5- 
inch Amidon ferrite rod 7 inches long. L2 is 6- 
tum link wound over center of L1. L4 and L5 are 
each 50 turns No. 26 enamel on T80-2 pow- 
dered-iron toroid cores, with 6 turns for links L3 
and L6. — D. DeMaw, Low-Noise Receiving An- 
tennas, QST, Dec. 1977, p 36-39. 



G S D 
MPF102 



CAPACITIVE ANTENNA— Combination of short 
whip antenna and broadband amplifier gives 
antenna covering entire range of 3 to 30 MHz 
without frequency selectivity. Q1 is 2N3819 FET 
source follower driving three-transistor ampli- 
fier using 2N918, 2N6008, or other 200-MHz 20- 
V NPN transistors to provide 30-dB gain. Circuit 
rolloff starts at 3 and 35 MHz. High gain of am- 
plifier makes combination simulate quarter- 
wave whip over entire frequency range. — R. C. 
Wilson, The Incredible 18" All-Band Antenna, 73 
Magazine, March 1975, p 49-50. 



e iu *B 

Y 



T 



J-'-ioOdF 

' I— 



n — i — ■'■ 

fh fh fh 



03^ , 






"''lOOpF 



■0 52B 

OUTPUT 



I 



4= 4.7mfd 



9v. x 



4= .01 




J WV 



'1K 



>1K 



•820 



120K 

t-^WV — •- 



.001 



100K 
-A/W- 



.001 68 K 
— 1( »— V\A, <- 



-® L® L® 



.001 



NOISE BRIDGE— Used with communication re- 
ceiver to measure impedance at antenna ter- 
minals or at end of transmission line, as re- 
quired for adjusting antenna matching and 
loading devices for desired impedance at spe- 
cific frequency. Consists of diode-connected 
transistor broadband-noise generator, 3-stage 
noise amplifier, and toroid transformer bridge. 



All transistors are 2N5129 or equivalent 2N5137 
or 2N5220. Try different transistors until highest 
noise output is obtained. Toroid core for trans- 
former is Vinch Indiana General CF102. Quad- 
rifilar winding has 4 1 i turns of four No. 28 
enamel wires twisted together, wound on core 
and connected as pn diagram. Noise bridge can 
also serve as wideband noise source for signal 




Receiver 



injection during troubleshooting in AF or RF cir- 
cuits, and as noise source for aligning RF cir- 
cuits. — J. J. Schuftz, An Improved Antenna 
Noise Bridge, CO, Sept. 1976, p 27-29 and 75. 



24 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



TRANSMITTER 



SHORT LENGTH OF 
COAXIAL CABLE 



.12 TURNS 24 AWG 
/ONFERRITE RING 



LOGARITHMIC WATTMETER— Single meter 
scale covers 1-1000 W, with equally spaced di- 
visions for 1, 10, 100, and 1000. This log scale 
makes it possible to measure very low reflected 
powers and very high forward powers simul- 
taneously with same percentage accuracy. 
Basis of operation is that voltage dropped 




across forward-biased 1N4062 silicon PN junc- 
tion diode is proportional to logarithm of cur- 
rent through it. For 50-ohm line, use 220 for R2 
and 27 for R3 and R4. For 75-ohm line, corre- 
sponding values are 180 and 33. Detector diodes 



are point-contact germanium rated at 80 PIV. 
Article gives construction details. Ground coax 
braid at one end only. Ferrite ring is 0.5-inch 
Milliard FX1596 or equivalent. — P. G. Martin, 
Some Directional Wattmeters and a Novel SWR 
Meter, 73 Magazine, Aug. 1974, p 17, 19-21, 23- 
24, and 26. 



1-kHz MODULATOR FOR VHF SOURCE— Used 
with 144-MHz signal generator driving VSWR 
bridge, for measuring and matching VHF anten- 
nas. R1 adjusts frequency of NE555 timer used 
in place of customary MVBR. Series-pass tran- 
sistor increases output of MVBR about 2 dB. — 
J. Reisert, Matching Techniques for VHF/UHF 
Antennas, Ham Radio, July 1976, p 50-56. 




GROUND TO RF 
GENERATOR 



SI POSITIONS 



S2 POSITIONS 
INOUCTANCE^H) 




C1-C3, incl. - Miniature 365-pF variable (Archer/ 

Radio Shack No. 272-1341 or equiv.) 
CR1 - IN34A or equiv. 

LI — 15 turns No. 24 enam. wire, close-wound on 

1/4-inch ID form. Remove form after winding. 
L2 - 28 turns No. 24 enam. wire on Amidon 

T-50-6 toroid core. Tap 7 turns from each end. 

(Amidon Associates, 12033 Otsego St N 

Hollywood, CA 91607.) 
L3 - 28 turns No. 24 enam. wire on Amidon 

T-50-2 toroid core. Tap at 5, 10 and 15 turns 

from L2 end. 
L4 — 36 turns No. 24 enam. wire on Amidon 

T-68-2 toroid core. Tap at 6, 12 and 18 turns 

from L3 end. 
M1 — to 1-mA dc meter, 1-1/2 inches square. See 

text. 
R1-R3, incl. — 51-ohm, 2-watt, 5-percent 

tolerance. 
R4 — Miniature 10,000-ohm control, audio or 

linear taper suitable. 



TRANSMATCH — Tapped variable inductance 
and three broadcast tuning capacitors are easily 
preadjusted to match low-power (QRP) trans- 
mitter to antenna for SWR of 1 in commonly 
used amateur bands. Resistance bridge is used 
only for initial determination of correct settings 
for C1, C2, C3, and S2 at each band to be used. 
Set S1 at 1, feed peak output of transmitter to 



J1 (5 W maximum), and adjust R4 for full-scale 
reading of M1. Next, connect 50-ohm resistive 
load between CR1-R1 junction and ground. 
Meter reading should now drop to zero, indi- 
cating null at 50 ohms. Move 50-ohm dummy 
load to J2, set SI at 2, and adjust settings of CI , 
C2, and C3 for zero deflection of meter. Note 
settings, then repeat for each other transmitter 



frequency to be used. Repeat procedure with 
antenna or feed line in place of dummy load, 
using smallest inductance that gives SWR of 1. 
After completing adjustments, set S1 to 3 to 
bypass bridge for normal transmitter opera- 
tion. — D. DeMaw, A Poor Ham's QRP Trans- 
match, QST, Oct. 1973, p 11-13. 



ANTENNA CIRCUITS 



25 



+ 40dB AMPLIFIER 



OSCILLATOR 



VfF CONVERTER— Voltage developed across S- 
meter is amplified by 741 opamp having gain of 
40 dB, so full-scale voltage of 100 mV becomes 
10 V at opamp output. This drives modulation 
input of 555 timer connected as free-running 
oscillator. Nominal 1-kHz output increases in 
frequency as drive current is reduced; con- 
versely, drop in frequency corresponds to 
stronger signal at S-meter. Developed for use as 
audible guide when tuning Yagi and other beam 
antennas for amateur radio operation. — G. Hin- 
kle. Closed Loop Antenna Tuning, 73 Magazine, 
Mav 1976, p 32-33. 



TO S-METER 
TERMINALS 




GAIN (dB)-20LOG (R2/RI) 
F- l.44/(R +2Rb)C 




0.2 fiVI TO 10 mW — Accurate low-power watt- 
meter uses small lamps as barretters for mea- 
suring RF power up to 10 mW from 1 to 500 
MHz. Applications include measurements of an- 
tenna gain, local oscillator frequency, VSWR, 
and filter response. Subminiature T-3/4 RF sen- 
sor lamps operate in bridge circuit with R1, R2, 
and R3. Voltage difference between bridge legs 
is amplified by opamp U1. Bridge current driver 
Q1 supplies current for balancing bridge. Equi- 
librium voltage of 3.5 V at V„ is fed to metering 
circuit including U2. Article covers calculation 
of values for calibration resistors R4-R10, which 
range from 5.715 to 7192 ohms. — J. H. Bowen, 
Accurate Low Power RF Wattmeter for High Fre- 
quency and VHF Measurements, Ham Radio, 
Dec. 1977, p 38-43. 



CONTROL 




ADDED PARTS 



ANTENNA ROTATOR— Developed for use with 
CDE TR-44 antenna control using low-voltage 
AC motor having pot for bearing indication. Cir- 
cuit eliminates need for holding control handle 
in position until antenna reaches desired bear- 



(X= RF CHOKE LOCATION IF NEEDED) 

ing. Uses 12-VDC 1000-ohm 1-A relays, Tl 
SN7274IL opamp U1, and wirewound 360° ro- 
tation command pot R7 operating from 14-V 
regulated supply of original control. When R7 is 
set to desired new heading, relay applies power 



I LIMM . ^ 

!^3 — <W)_ 

limit) (mcA— 



"37 



1 at 



ROTOR 
POTENTIOMETER 



to motor for proper direction, and drops out 
when antenna reaches desired heading. One 
relay is used for each direction of rotation. 
Opamp is connected in differential-input mode 
that responds only to difference voltage be- 
tween wipers of pots R7 and R8. Polarity of 
opamp output depends on polarity of input volt- 
age difference. CR3 and CR4 energize K1 or K2 
depending on polarity of error signal. R9 and R3 
serve to balance voltage difference remaining 
when R7 and R8 are at travel limits. R9 also nulls 
offset present when there is no input to U1 . Ac- 
curacy is about 5°. Diodes are 100-PIV 0.5-A sil- 
icon. — K. H. Sueker, Automating the TR-44 An- 
tenna Rotor, QST, June 1973, p 28-30. 



26 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



S0239 




ALL DIODES 1N270 



INSTANT VSWR BRIDGE— Modified 190B Tek- 
tronix constant-amplitude signal generator is 
combined with 50-ohm resistance bridge to 
give stable high-accuracy instrument for mea- 
suring voltage standing-wave ratio as guide for 
tuning antennas. Range is 160 meters through 
10 meters. Trim Rx so incident or forward volt- 



Si POSITION 
I - INC 

2- REF 

3- hi 

4- M 

age at position 1 of SI equals reflected voltage 
at position 2. Article gives chart for finding 
VSWR. Step-by-step procedure for modifying 
signal generator is given. — D. Sander, Make An- 
tenna Tuning a Joy, 73 Magazine, May 1978, p 
134-136. 




FIELD STRENGTH AT 7 MHz— Operates from 
single dry cell. Meter can be calibrated in deci- 
bels with Hewlett-Packard 606A or equivalent 
signal generator. Jack permits remote meter- 
ing. LI is 5 turns, and L2 is 30 turns wound on 
Amidon T68-2 core.— R. W. Jones, A 7-MHz Ver- 
tical Parasitic Array, QST, Nov. 1973, p 39-43 
and 52. 




-N- 



CR1 
IN400I 



Tl METER TRANSFORMER 

FROM 

H4M-M CONTROL 



u. 



10 
-VA. 1 



LJTc* 



R3 
IJBK 




RIGHT 



a 



X 



GROUND CONNECTION 
AT ROTOR 



CIRCUIT COMMON 




— wv- 

RIZ 
3SK 



-7\(r 




. TO 
V TIMING 
' CIRCUIT 



ANTENNA POSITION CONTROL— IC logic pro- 
vides automatic brake release and positive po- 
sition control for commercial Ham-M antenna 
rotator. Regulated power supply drives bridge 
having position-sensing pot R8 in rotator and 
R9 in control box. When antenna is in desired 



position, wiper voltages of pots are equal. 
When R9 is set to new position, voltage differ- 
ence is amplified by error amplifier U2. Com- 
parators U3 and U4 determine rotation direc- 
tion needed for rebalance and deliver logic 
circuits to timing circuit (also given in article) 



that drives motor and brake release relays. 
Timer prevents jamming of circuit by operator 
error.— P. Zander, Automatic Position Control 
for the HAM-M Rotator, Ham Radio, May 1977, 
p 42-45. 



ANTENNA CIRCUITS 



27 




M1 
0-50 



Band 

LI OiH) 
C2 (ph) 
C3 (pF) 
Miller 
Coil 



160 M 



ALTERNATIVE 

INPUT 

METHOD 

SO M 



40 M 



100 (Nom.) 25(Nom.) 

25 25 

100 100 

4409 4407 



20 M 



15 M 



10M 



10 (Nom.) 


2.2 (Nom.) 


1.3 (Nom.) 


0.5 (Nom.) 


15 


15 


10 


10 


68 


68 


47 


47 


4406 


4404 


4403 


4303 



FIELD-STRENGTH METER— Useful for antenna 
experiments and adjustments in amateur bands 
from 160 to 10 meters. Increasing size of pickup 
antenna increases sensitivity. Far-field mea- 
surements are made with alternate input cir- 
cuit, in which reference dipole or quarter-wave 
wire cut for frequency of interest is connected 
to input link. Diodes are 1N34A germanium or 
equivalent. Ml is 50 pA. Table gives values of 
tuned-circuit components for six amateur 
bands. — D. DeMaw, A Simple Field-Strength 
Meter and How to Calibrate It, QST, Aug. 1975, 
p 21-23. 



MODULATION MONITOR— Provides off-the-air 
monitoring of RF signals up to 200 MHz by rec- 
tified detection of AM signals and by slope de- 
tection of FM signals. Can also be used as signal 
tracer, audio amplifier, or hidden-transmitter lo- 
cator. High-gain audio amplifier has low-noise 
cascode input stage and output stage driving 
headphone or loudspeaker. S, selects RF signals 
detected by D, or AF applied to J 2 . L, is 4 turns 
No. 18 for monitoring 75-150 MHz. Will also 
monitor VHF transmissions from pilot to 
ground stations while in commercial aircraft, 
using 24-inch wire antenna near window and 
earphone. Passive-type receiver is safe in air- 
craft because it has no oscillators that could in- 
terfere with navigation equipment. — W. F. Spli- 
chal, Jr., Sensitive Modulation Monitor, CQ, 
Jan. 1973, p 59-61. 





TO UNIT 
UNDER TEST 



CI, C2 small capactive tab required for balance 

C3, C4 0.001 liF (small disc ceramic or chip capacitor) 

CR1 1N82A or equivalent germanium diode 

Jl, J4 UG-290A/U BNC connector 

J2, J3 UG-58/U type-N connector 

Rl, R2 47 to 55 ohms, matched 

R3 51 ohms, '/4-watt carbon composition 

R4, R5 10k ohms, '/4-watt carbon composition 

R6 100k ohms, '/4-watt carbon composition 




VSWR BRIDGE— Works well through 450 MHz 
for measuring and matching VHF and UHF an- 
tennas. H identical load impedances are placed 
at J2 and J3, signals at opposite ends of R3 are 
equal and in phase and there is no output at J4. 
If impedances are different, output proportional 



to difference appears at J4. Impedance values 
can be from 25 to 100 ohms, although circuit is 
designed for optimum performance at 50 
ohms. — J. Reisert, Matching Techniques for 
VHF/UHF Antennas, Ham Radio, July 1976, p 
50-56. 



Q MULTIPLIER FOR LOOP— Improves perfor- 
mance of loop antenna on 40, 80, and 160 me- 
ters. Feedback control is obtained with adjust- 
able single-turn loop L3 coupled to LI, and 
receiver input is taken from L2. L3 is rotated 
within field .of L1 to adjust amount of regener- 
ation, optimize circuit Q, and make directional 
null more pronounced. Article gives loop con- 
struction details. Ground lower end of 100K re- 
sistor to provide ground return for FET. — K. Cor- 
nell, Loop Antenna Receiving Aid, Ham Radio, 
May 1975, p 66-70. 



28 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



AMIOON T50-2 
14 TURNS/WINDING 
NO. 28 WIRE 




RF NOISE BRIDGE— Improves accuracy and 
measurement range for impedance measure- 
ments from 3.5 to 30 MHz, particularly resistive 
and reactive components of high-frequency an- 
tennas. Accuracy is 3 ohms RMS. Wideband 
noise, generated in zener followed by three- 
transistor amplifier, is injected into two legs of 
bridge in equal amounts by toroidal trans- 
former having quadrifilar windings. With un- 
known impedance connected and detectoMany 




communication receiver) set to desired fre- 
quency, reference impedances (250-ohm non- 
inductive pot and 360-pF variable capacitor) are 
adjusted for deepest possible null. Value of un- 
known impedance is then equal to parallel com- 
bination of references. Article covers construc- 
tion and calibration. — R. A. Hubbs and A. F. 
Doting, Improvements to the RX Noise Bridge, 
Ham Radio, Feb. 1977, p 10-20. 



LOOP PREAMP — Loop for lower-frequency am- 
ateur bands is connected to gate of HEP802 FET 
and output to receiver is taken from FET source. 
CI is two-gang variable capacitor from old 
broadcast radio, with stators in parallel to give 
600 pF. Article gives loop data for 40, 80, and 1 60 
meters and for high end of broadcast band. For 
40 and 80 meters, use 18-inch square loop with 
2 turns spaced 1 A inch. Ground lower end of 
100K resistor to provide ground return for 
FET. — K. Cornell, Loop Antenna Receiving Aid, 
Ham Radio, May 1"75, p 66-70. 



TO RF 
OUTPUT 
(COAX ^ 

CONNECTOR) rh 



6 pF 



IN38B 

-w- 



222 



I.IK 
-VW- 



-1 Wr- 



1.0047 llF 



0-1 

-.0047 

» JJF 



RF OUTPUT INDICATOR— Designed for use 
with amateur radio transmitters. Pot is adjusted 
for maximum desired indication on band used. 
For 20-10 meters, 6-pF capacitor is adequate. 



On lower bands (80-40 meters), use 7 or 12 pF 
instead.— Novice Q & A, 73 Magazine, Holiday 
issue 1976, p 20. 




RADIATED-FIELD METER— Gives quick check of 
overall transmitter performance, including an- 
tenna system. Meter can be 1 mA, but 0-200 /iA 
or 0-50 iiA will be more sensitive. The longer 
the reference antenna used, the greater will be 
the sensitivity of the meter. Keep lead lengths 
short. If measurements for various transmitter 
inputs are recorded when transmitter is work- 
ing properly, they can serve as guide for later 
troubleshooting. — E. Hartz, Is My Rig Working 
or Not?, 73 Magazine, Oct. 1976, p 56-57. 




FB 
LI 



as large as possible, consistent with good oscillator 

starting (100 pF typical) 

ferrite bead 

9 turns no. 24 (0.5mm) on Amidon T-37-12 toroid 

core; tapped 3 turns from cold end 



L2 15 turns no. 28 (0.3mm) on Amidon T-25-12 toroid 

core 
L3.L4 4 turns no. 24 (0.5mm), W (6.5mm) inside diameter, 

y>" (6.5mm) long 
Yl 72-MHz, 5th-overtone, series-mode crystal 



144 MHz FOR VSWR BRIDGE— Modulated sig- 
nal source provides 10-mW CW output and 5- 
mW modulated output at modulation fre- 
quency of 1000 Hz. Spurious and harmonic out- 
puts are 40 dB below desired output. 72-MHz 



crystal oscillator is followed by doubler stage.** 
Oscillator runs continuously while doubler is 
keyed with simple ON/OFF square-wave keying. 
Freedom from load variations is obtained with 
double-tuned output filter providing up to 6-dB 



attenuation between generator and load. Use 
regulated power supply or batteries. — J. Rei- 
sert. Matching Techniques for VHF/UHF Anten- 
nas, Ham Radio, July 1976, p 50-56. 



ANTENNA CIRCUITS 



29 



10 in L0 WIRE OR ROD 




LOOP OF NO. 12 AWS WIRE 
ABOUT 10 TO 12 in. IN 01 A. 



* ADDITIONAL FIXED MICA 
CAPACITOR AS NECESSARY 
TO TUNE LOOP ON DESIRED 
BAND. 



90-70.0. UNE 
TO RECEIVER 



* — + 9-15 VDC 



ACTIVE ANTENNA— Uses tuned loop with rel- 
atively low Q for broadband operation over one 
amateur band, phase-coupled by FETto 10-inch 
vertical sensing antenna to give unidirectional 
reception pattern. Loop is tuned to either 80 or 
40 meters by trimmer capacitor at its base. Out- 
put of loop is coupled to another 3N142 FET 
used as source follower, to isolate output of 
loop from heavy loading effect of 50-ohm trans- 
mission line going to receiver. Performance is 
comparable to that of full-size quarter-wave 
vertical antenna on 40 meters. Battery source 
can be used because drain is only about 2 mA. — 
J. J. SchuKz, An Experimental Miniature An- 
tenna for 40 to 80 m, 73 Magazine, June 1973, 
p 29-32. 



PROTECTION FOR QRP TUNING— Simple resis- 
tive SWR bridge provides dummy load, relative 
power output indicator, and safe method of tun- 
ing transmitter without destroying transistors 
because of mismatched load. Input divider R1- 
R4 has total resistance of 50 ohms, using 1 £-W 
composition resistors, for dissipating transmit- 
ter output when SI is in TUNE position. M1 in- 
dicates relative power applied to this load. An- 
tenna is connected through Transmatch, and 
antenna tuner is adjusted for minimum deflec- 
tion or lowest SWR. R5 isolates transmitter 
from antenna. With S1 in OPERATE position, M1 
indicates relative power output into antenna. — 
A. S. Woodhull, Simplified Output Metering 
Protects QRP Transmitters, QST, April 1977, p 
57. 



TRANSMITTER I 




6 OPERATE 

-o — _ 

l^TUNE 



R5 
100 
1W 

-AA/V 





r< to 

I TRANSMATCH 




NS EW 

CHANNEL CHANNEL 



♦ CRT- 8 CRT- 1 1 



♦ CRT- 7 CRT- 10 



ADDED FOR GAIN 

8 PHASE BALANCING 



10-kHz SFERICS RECEIVER— Developed to 
measure direction and strength of atmospheric 
electromagnetic radiation (sferics) associated 
with severe weather conditions, for detection 



and tracking of tornadoes. Signals from crossed 
loop antennas feed deflection amplifier of CRO. 
Article covers problems involved and gives cir- 
cuit for sense amplifier that resolves 180° am- 



biguity fn oscilloscope pattern. — R. W. Fergus, 
A Ham Radio Severe Weather Warning Net, 73 
Magazine, Sept. 1974, p 27-30, 32, 34-36, and 
38-39. 



30 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



4f &$yU- 



V 




Ci, C3— 5 mmf tubular or disc ceramic. 

C2— 5-120 mmf variable capacitor. Millen 

#20100. 
C 4 , Cj, C4— .0047 mf tubular or disc ceramic 

capacitor. 
C7— 1.8-2.2 mc— 250 mmf tubular ceramic 

or mica capacitor. 
Cs— 2.2-3.2 mc— 100 mmf tubular ceramic or 

mica capacitor. 
1,-3.2-8.5 mc-22 t. #22 on 4y 2 ". X 1/4" 

"d. ferrite rod— see text. 



l 2 -6.3-17 mc-16 t. #22 on 1" I. X 1/4" 
d. ferrite rod. 

l 3 _14-38 mc-6 t. #22 on 5/8" I. X 1/4" 
d. ferrite rod. 

L 4 — 26-70 mc— 7 t. #22 air-wound, self- 
supporting, 1/4" i.d. 

Lj— 60-150 mc— 2 t. #22 air-wound, self- 
supporting, 1/4" i.d. with 3/16" spacing 
between turns, spread or squeezed as 
needed to cover v.h.f. range. 



RF MAGNETOMETER— Measures RF radiation 
and current distribution for antennas, transmis- 
sion lines, ground leads, building wiring, and 
shields. Can also be used as sensitive portable 
field-strength meter. Will indicate orientation of 
field. High-Q circuit is tunable from 1.8 to 150 
MHz for indicating frequency of fields produced 
by RF harmonic. Applications include detecting 
reradiation from rain gutters, metal fencing, 
towers, and guy wires that are distorting an- 
tenna field patterns, and detecting radiation 
from ground leads, appliance power cords, and 
hidden building wiring. When used as probe, 
will accurately pinpoint leakage of RF energy 
from joints, holes, or slots in shielded enclo- 
sures. Operation is similar to absorption-type 
wavemeter, except that pickup coil is electro- 
statically shielded by slotted aluminum IF trans- 
former can to eliminate capacitive coupling. In- 
ductor is wound on ferrite coil to give very high 
Q as pickup element. — W. M. Scherer, An R. F. 
Magnetometer and Field Strength Meter, CO, 
April 1971, p 16-20. 



DIRECTIONAL WATTMETER— Gives 10% accu- 
racy between about 100 kHz and 70 MHz. Full- 
scale values of ranges are 1, 10, 100, and 1000 
W. Low resistance in secondary circuit of cur- 
rent transformer is split into two equal parts, so 
sum and difference voltages are available at 
ends of secondary. Meters then indicate for- 
ward and reflected power values. For 50-ohm 
line, use 220 for R2 and 27 for R3 and R4. For 75- 
ohm line, corresponding values are 180 and 33. 
Detector diodes are point-contact germanium 
rated at 80 PIV. Article gives construction de- 
tails. Ground coax braid at one end only. Ferrite 
4ecring is 0.5-inch Mullard FX1596 or equiva- 
lent. — P. G. Martin, Some Directional Wattme- 
ters and a Novel SWR Meter, 73 Magazine. Aug. 
1974, p 17, 19-21, 23-24, and 26. 



AUD 

INPi 



" O-, ,— I 




SHORT LENGTH Of 
COAXIAL CABLE 
TRANSMITTER \ 



^ 



12 TURNS 24 AWG 
^ON FERRITE RING 



R3 T R4 - . 



50 uA FSD V y °yi 50uA FSD 



MATCHED r^-rC^TSn 
DIODES I yv SIB P 




_\_ iao 7 oJOOOW 
I lOWCJ oioowj, 

l\ li 



i'aK / I50K / 
47K 470K 



\ooi?r 04 

AC , 2N5459 




ANTENNA Q 



O.I11F 



ABC 

THRESHOLD 

ADJUST 







A-F 
AMPLIFIER 



T 




0.47^ m s 



AGC AND 

PIN CURRENT 

SOURCE 



PIN DIODE ATTENUATOR— Designed for inser- 
tion between antenna and input of any HF re- 
ceiver to improve adjacent-channel selectivity 
by providing attenuation ahead of mixer for en- 
tire tuning range. Hewlett-Packard 5082-3379 
PIN diode has very low impedance when con- 
ducting and very high impedance when bias 



current is small. NPN transistor Q1 provides 
over 100 mA as current source to PIN diode. Q1 
is driven by AGC circuit through JFET buffer 03. 
AGC voltage is derived from top of audio gain 
control in receiver for rectification, with 200 
mVRMS at input of opamp U1 giving maximum 
attenuation. Center tap of T1 (any small AF 



transformer) can be grounded. CR1 and CR2 are 
germanium diodes. Article also gives circuit of 
IF system using cascaded 9-MHz crystal filters 
to improve selectivity further and provide over- 
all AGC control range of 70 dB. — M. Goldstein, 
Improved Receiver Selectivity and Gain Control, 
Ham Radio, Nov. 1977, p 71-73. 



ANTENNA CIRCUITS 



31 



INPUT FROM MPS65I4 

ORIGINAL s~~>~-*- 

AMPLIFIER ., f\y\ 




BROADBAND NOISE AMPLIFIER— Developed 
for use with antenna noise bridges for mea- 
surements at 20 meters. Provides 35 to 50 dB 
additional gain, not entirely constant over use- 
ful range of 1.8 to 30 MHz. Three strong feed- 



AC FEEDBACK 



back loops are introduced between driver and 
final amplifier. Use transistors specified, be- 
cause substitutions may cut overall gain by 10 
to 20 dB. — A. Weiss, Noise Bridge, Ham Radio, 
May 1974, p 71-72. 



IMEG 
SENSITIVITY 




FIELD-STRENGTH METER— Easily assembled 
for checking performance of amateur radio 
transmitter and its antenna system. — Circuits, 
73 Magazine, Jan. 1974, p 128. 



SHORT LENGTH OF 
COAXIAL CABLE 
TRANSMITTER \ 

<^3 



12 TURNS 24 AWG 
/ON FERRITE RING 




SWR METER — Gives direct measurement of 
standing-wave ratio on transmission line, in- 
dependent of absolute power levels and of fre- 
quency. Voltages of 1N4002 silicon diodes are 
proportional to logarithms of their currents, 
which in turn are proportional to forward and 
reflected voltages. Meter scale is nonlinear, 
with maximum sensitivity as SWR approaches 
1:1. For 50-ohm line, use 220 for R2 and 27 for 



R3 and R4. For 75-ohm line, corresponding val- 
ues are 180 and 33. Detector diodes are point- 
contact germanium rated at 80 PIV. Article gives 
construction details and calibration curve. Fer- 
rite ring is Mullard FX1596 or equivalent, with 
0.5-inch outside diameter. Ground coax braid at 
one end only. — P. G. Martin, Some Directional 
Wattmeters and a Novel SWR Meter, 73 Mag- 
azine, Aug. 1974, p 17, 19-21, 23-24, and 26. 



r 



56S2 
v/W- 



RFC 
1mh 



r~ 



-A 



1N34A/ 
1N60or' 
similar 



.001 t= 



L 2 
_rv-Y-v\__ 



390pf 

S.M. 



Rj 

56fi 

W\ — " 

CR 2 
1N34A/ 
1N60or 
similar 



4= .001 



C 2 



DUAL-RANGE RF WATTMETER— Uses circuit 
which is not frequency-sensitive, so calibration 
can be accurate over wide frequency spectrum. 
Ranges are 0-1 and 0-10 W. L 2 is T-50-2 toroid 
wound almost full with No. 28 enamel, leaving 
only room for 2-turn link L,. C, and C 2 are 3-20 
pF trimmers. Article covers calibration and use 
and gives table for reading SWR by comparing 




watts FORWARD with watts REFLECTED.— A. 
Weiss, The Silk-Purse In-Line Wattmeter, CO, 
May 1977, p 50-52 and 74-75. 



jiz 



W ; ; 



rh rh 



~X 



TUNED RADIATED-FIELD METER— Provides 
quick check of transmitter performance and ap- 
proximate check of frequency. Values for L1 and' 
C1 are chosen to cover desired frequency range. 
Meter can be 1 mA or 200 pA. Keep lead lengths 
short.— E. Hartz, Is My Rig Working or Not?, 73 
Magazine, Oct. 1976, p 56-57. 




FIELD-STRENGTH METER— Developed for tun- 
ing all types of antennas, from mobile whips to 
four-element quads. Avoids shielding and other 
problems of switched T pads for calibrated at- 
tenuator by first detecting RF, then attenuating 
DC output. Technique has added advantage 
that circuit is no longer frequency-sensitive. To 
cover 13-24 MHz, L2 is 11 turns spaced out to 
about 1 inch, with 2 turns over top for L1 . D1 can 
be any diode such as 1N34. RI serves as cali- 
brated attenuator, with R2 in series giving 0-dB 
point at junction. Article covers construction 
and operation. — J. L. Iliffe, An Amplified, Cali- 
brated, Signal Strength Meter, 73 Magazine, 
June 1973, p 85-86. 



CHAPTER 3 

Audio Amplifier Circuits 



Includes preamps for all types of inputs and AF amplifiers with power outputs 
up to 90 W and bandwidths up to 50 kHz, most using transistors with or 
without opamps and ICs. Circuits include variety of methods for reducing 
distortion and eliminating switching transients. See also Audio Control, 
Receiver, and Stereo chapters. 



6 TO 18 VOLTS 



500-OHM INPUT— Simple audio amplifier hav- 
ing high gain, low noise, and excellent temper- 
ature stability can be used as mike booster, first 
AF amplifier stage in receiver, or for other 
preamp applications. With values shown, cir- 
cuit will amplify down to about 10 Hz. To In- 
crease low-frequency cutoff for speech ampli- 
fier, reduce C2 to 1 tiF or less. — E. Dusina, Build 
a General Purpose Preamp, 73 Magazine, Nov. 
1977, p 98. 



INPUT °- 




OUTPUT 

2SD96 



CDC13000-1D 



INPUT-*— | ( — » 



O.Gtfmfd 



+ 14V 



TO TONE CONTROLS " 



COMPLEMENTARY-SYMMETRY AMPLIFIER— 
Simplified version of circuit takes advantage of 
fact that PNP and NPN transistors require sig- 
nals of opposite polarity to perform same func- 




FEEOBACK TO TONE CONTROLS 



tion. Bases of output transistors are fed in par- 
allel, with loudspeaker connected to common 
terminal of transistors. Drawback is difficulty of 
locating matched PNP and NPN transistors. — J. 



J. Carr, Solid-State Audio: A Review of the Lat- 
est Circuitry and General Troubleshooting Pro- 
cedures, Electronic Servicing, Aug. 1971, p 38- 
43. 



32 



AUDIO AMPLIFIER CIRCUITS 



+ 40V to 45V 





30-W — Designed for use with active filter cross- high-frequency channel, C 3 and C 4 are 10 §if. 

over networks for three loudspeakers. For low- Article includes circuit for active filter net- 

est-frequency channel, C 3 is 150 /tF and C 4 is 50 work.— D. C. Read, Active Filter Crossover Net- 

/*F. For middle channel, C, and C 4 are 25 /tF. For works. Wireless World, Dec. 1973, p 574-576. 



-vcc 



HAMMER DRIVER— Signetics 540 power driver 
handles either push-pull or single-ended induc- 
tive loads such as relays, solenoids, motors, and 
electric hammers. In push-pull connection 
shown, load is driven in either positive, nega- 
tive, or both arms of output. Either output can 
be selected by appropriate choice of input pulse 
polarity. Supply can be ±5 to ±25 V. — "Signet- 
ics Analog Data Manual," Signetics, Sunnyvale, 
CA, 1977, p 764. 



Vs 

o 




270 



'~ZL 



270 




20^F 

2.7 

r -VW- 


9 

>w 13 




i 
— * ' 



0.05mF 



10,11,12 




3.5-W BRIDGE AMPLIFIER— Bridge connection 
of National LM388 power opamps provides 3.5 
W to 8-ohm loudspeaker when using 12- V sup- 



V S = 6V R L =4n P o = 10W 
V s = 12V R L = 8fi P » 3.5W 

ply. With 6-V supply and 4-ohm load, maximum 
power is 1 W. Coupling capacitors are not re- 
quired since output DC levels are within several 



tenths of a volt of each other.— "Audio Hand- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 4-37-4-41. 



34 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




LOW-COST 30-W— Economical compromise 
gives 30 W into 8-ohm load at 0.1% distortion 
(mainly second harmonic) and hum level of -50 
dBW. Article covers design and operation of cir- 
cuit in detail. — P. L. Taylor, Audio Power Am- 
plifier, Wireless World, June 1973, p 301-302. 



all resistors± 5°/o VsW unless stated 
• - ± 2°/. 



70-dB GAIN WITH 1.5 V— Operates from single 
penlight cell at current drain of 0.5 mA. Ideal as 
self-contained unit inserted in microphone 
cable. Q2-Q4 form 70-dB voltage amplifier. Q5 
is detector, and Q6 is emitter-follower driving 
AGC transistor Q1 . 3-dB bandwidth is about 100 
Hz to 8 kHz. Full output is about 200 mVRMS, 
while low output terminal is 1 mVRMS. — C. 
Hall, Low-Voltage Audio AGC Amplifier, Ham 
Radio, Dec. 1973, p 32-34. 




(+12 TO +20V) 




2 W WITH IC— Uses Motorola MFC9020 audio 
power amplifier to give maximum output of 
about 2 W for 16-ohm loudspeaker. Used in au- 
topatch system for FM repeater. — R. B. Shreve, 
A Versatile Autopatch System fqr VHF FM Re- 
peaters, Ham Radio, July 1974, p 32-38. 



AUDIO AMPLIFIER CIRCUITS 



35 



•39* 



INPUT 

o 



<i 50 v F 



-F- 



27K 

-Wv — *■ 



-I 120 

i' — IJ — wv- 



-0*12V 




5000 pF 



560 

4 — * VA •— " 



27 K 

-VW- 

.001 



Q50.F. 



H}— o«l 



■fc 



^L 



AUTO RADIO AMPLIFIER— Circuit shown per- 
mits operation of Signstics NE540 power driver 
from single-polarity 12-V supply of auto. Bipolar 
supplies for differential inputs of 540 are 
achieved by returning inputs to half of available 
supply or 6 V. Load is AC coupled because am- 
plifier has DC gain of 1, and amplifier output is 
therefore 6 VDC. 39-ohm supply resistors are 
selected for minimum crossover distortion. — 
"Signetics Analog Data Manual," Signetics, 
Sunnyvale, CA, 1977, p 764. 



HIGH-GAIN IC WITH TRANSISTOR— High input 
impedance of RS741C opamp permits use with 
any general-purpose crystal microphone. R2 is 
volume control, and R3 controls gain and fre- 
quency response of IC. Power transistor stage 
drives loudspeaker directly, without output 
transformer. — F. M. Mims, "Integrated Circuit 
Projects, Vol. 6," Radio Shack, Fort Worth, TX, 
1977, p 79-88. 





POWER AMPLIFIER WITH ERROR TAKEOFF— 
Voltage proportional to distortion is amplified 
for use in reducing nonlinear distortion at out- 
put, in circuit developed for use as single-ended 
power amplifier. Power Darlingtons are MJ4000 
and MJ4010, and both opamps are 741. Preset 
5K pot is adjusted initially for minimum distor- 
tion. Article gives theory of operation and de- 
sign equations. — A. M. Sandman, Reducing 
Amplifier Distortion, Wire/ess World, Oct. 1974, 
p 367-371. 



36 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




VOLTAGE GAIN 
R 7 +R 8 



CURRENT LIMITING 
650 mV 



POWER LIMITING 
R 2 = R5 56S2 
V CC 
J * 3mA 




MOTE-. 
Pins 1, 7 and 8 not connected. 



HEADPHONE AMPLIFIER— Can be used with 
FM tuner in place of more expensive audio am- 
plifier. For stereo, use one LM386 circuit for each 
channel. Can be mounted directly on head- 
phones if weight of battery is not objectiona- 
ble. — J. A.Sandler, 11 Projects under $11, Afoo*- 
ern Electronics, June 1978, p 54-58. 



35 W — Signetics 540 drives complementary 
output transistors to give high output current 
for driving 8-ohm loudspeaker. Feedback is ad- 
justed to give AC gain of 40 dB. Gain rolls off to 
unity at DC to prevent DC offset voltages from 



being amplified to level that might damage 
loudspeaker circuit. Power limiting is provided 
by placing resistor network around output 
stage. — "Signetics Analog Data Manual," Sig- 
netics, Sunnyvale, CA, 1977, p 762-763. 



H5V 



R2 
I0K 



SEE BOTTOM VIEW 




JT^ 



S CONSTANT 
CURRENT 
ADJ. 



D S G 



R3 
IMEG 
-w«— - 



UK 



47K 



OSCILLATOR 
FEEDBACK 
IK ® ADJ. 
-*$& •— 



IN4454'S 




motorola/ 
MPF I02 HEP8Q2 

BOTTOM VIEW 

PREAMP WITH TEST TONE— Built around Sig- 
netics N5558V dual opamp or equivalent Mo- 
torola MC1458CP2, National LM1458, or Texas 
Instruments SN72558P. First half of opamp is 
used either as gain stage for increasing voltage 
level of carbon microphone or as AF Wien- 




33K 
— w\, 



bridge tone oscillator, depending on position of 
S1. Frequency is determined by values of C1, C2, 
R4, and R5. Silicon signal diodes form nonlinear 
control element. Adjust R6 until oscillator out- 
put at TP1 is 10 V P-P. FET provides constant 
current through variable resistance of carbon 



microphone, to give audio input voltage. Sec- 
ond opamp is active low-pass filter with 3.3-kHz 
cutoff, rolloff of 12 dB per octave, and voltage 
gain of 10. — H. Olson, An IC Mike Preamp That 
Doubles as a Tone Generator, 73 Magazine, 
March 1974, p 45 and 47-48. 



AUDIO AMPLIFIER CIRCUITS 



37 



■0+15V 




HEADPHONE OPAMPS — Dual low-noise 4558 R. J. Apfel, Power Op Amps— Their Innovative 

opamp provides gain and reduces system noise Circuits and Packaging Provide Designers with 

and distortion, while 759 power opamp sup- More Options, EDN Magazine, Sept. 5, 1977, p 

plies output power of 0.7 W into 16-ohm load 141-144. 
with less than 0.1% total harmonic distortion. — 



LEFT SI50K] 

IN 




U 1 ?n.. f 



■f • 0+I2 V 



I8OKJI0K? IK< 



i5ok; 

0.0l M F O.OI/iFO.OI^F 

-Hh-rHhH 



20/.F 
- I2V 



44300 



I0K< 



I80K< I0K< IK< I00K 



056 M F 



390K> I0K> IK> I00K 



0.22,. F 



0.033,iF=p 



I0K I0K 



I50K 



270 K5 




[j^-ih h 



270KJ 



I80K 
I0K5 



ALL RESISTORS 
I/2 W, 5% 



I2V 

+ I0K I0K I0K 
-■- - •-- ■• vVV ». 



:i:0.22 M F 



0.033^F: 



0.56^F 



ALL N0N -ELECTROLYTIC 
CAPACITORS 5% 



ALL TRANSISTORS 
2N2925, OR EOUIV. 



54300 

-im-ii- 



O.OI^F O.OLf O.OI^F 
I50K 




I80K? IOK? \KZ IOOK 



o»I2V 



CROSSOVER FOR 20-Hz SUBWOOFER— Used 
at channel outputs of stereo system when re- 
producing music down to 20 Hz as synthesized 
by electronic function generators. Active cross- 
over network drives subwoof er (low-bass loud- 
speaker) connected in bridged-center configu- 
ration, for handling sounds below range of 
normal woofer. Crossover consists of third- 






2 




1-W CLASS B— Audio application of CA3020A 
wideband power amplifier provides 1-W output 
to loudspeaker load through AF output trans- 
former with 10% total harmonic distortion. V CC i 
is 9 V, and V CC2 is 12 V. With CA3020, both sup- 
ply voltages are 9 V and maximum power out- 
put is 550 mW. Sensitivity is 35-45 mV. — "Lin- 
ear Integrated Circuits and MOS/FET's," RCA 
Solid State Division, Somerville, NJ, 1977, p 
105. 



order Butterworth (18 dB per octave) networks 
providing 20-Hz cutoff along with 100-Hz cross- 
over. Response of subwoofer should extend 
one octave above crossover. One advantage of 
active crossover is freedom from transient in- 
termodulation distortion. — W. J. J. Hoge, 
Swftched-On Bass, Audio, Aug. 1976, p 34-36, 
38, and 40. 




46-dB GAIN— Single National LM386 power 
amplifier provides gain of 200 V/V at maximum 
output power of 250 mW for 12-V supply. Op- 
tional 0.05-/U.F capacitor and 10-ohm resistor 
suppress bottom-side oscillation occurring dur- 
ing negative swing into load drawing high cur- 
rent. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 4-30-4-33. 



V,nO 




HIGH INPUT IMPEDANCE— Use of JFET as iso- 
lator boosts input impedance of opamp to 22 
megohms for low-frequency input signals. 
Impedance drops to 3.9 megohms as frequency 
increases to about 20 kHz. Overall gain of circuit 
is about 45 dB when using 18-V supply. — 
"Audio Handbook," National Semiconductor, 
Santa Clara, CA, 1977, p 4-21-4-28. 



38 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 9VTO + I5V 
O 




16 OHMS IW V S -±9V 
32 OHMS SW kt • 1 15V 



2-W MONITOR — Fairchild 759 opamp provides 
1-W AF output when supply is ±9 V and loud- 
speaker is 16 ohms, and 2 W with ± 15 V and 32- 
ohm loudspeaker. Use heatsink. Gain is 20 for 
values shown, with response rolled off at 15 kHz 
by CI. — W. Jung, An IC Op Amp Update, Ham 
Radio, March 1978, p 62-69. 



60 W WITH DC-COUPLED OUTPUT— Q6 is Mo- 
torola MJE6044 complementary Darlington 
output transistor, and Q7 is MJE6041. Q1 and 
02 are MD8002 dual transistor, Q3 is MPS-A56, 
Q4 is MPS-A13, and Q5 is MPS-A06. For 8-ohm 
loudspeaker, supply is ±36 V with 6.2K for R4, 
430 ohms for R5, and 33K for R7. Output center 
voltage must be maintained at VDC to ensure 
maximum signal swing and prevent DC voltage 
from acting on loudspeaker. Frequency re- 
sponse is 10 Hz to 50 kHz for -1 dB points. Same 
circuit is used with different components for 
other powers down to 15 W and for 4-ohm loud- 
speaker.— R. G. Ruehs, "15 to 60 Watt Audio 
Amplifiers Using Complementary Darlington 
Output Transistors," Motorola, Phoenix, AZ, 
1974, AN-483B, p 5. 




#20 Enameled Wire 
Close Wound on 
10 !2/2 W Resistor 



OV cc 



IS V 

I 



® © © 



NOTE: 

TRANSISTORS pi, p2,p3 AND nl,n2, n3 ARE 
PARALLEL -CONNECTED WITH Q8 AND 0I2, 
RESPECTIVELY, OF THE CA3I30 




50-kHz BANDWIDTH— Three transistor pairs in boost current-handling capability about 2.5 kHz for 3 dB down.— "Circuit Ideas for RCA Lin- 
CA3600E array are parallel-connected with out- times. Use of feedback gives closed-loop gain ear ICs," RCA Solid State Division, Somerville, 
put stage of CA3130 bipolar MOS opamp to of 48 dB. Typical large-signal bandwidth is 50 NJ, 1977, p 12. 



AUDIO AMPLIFIER CIRCUITS 



39 



60 W WITH AC-COUPLED OUTPUT— Uses Mo- 
torola complementary Darlington output tran- 
sistors, with MJE6044 for Q5 and MJE6041 for 
Q6. For 8-ohm loudspeaker, Q1 is MPS-A06, 02 
is MPS-A56, 03 is MPS-A13, and Q4 is MPS-A06. 
Supply is 72 V. R5 is 220 ohms, and R7 is 68K. 
Same circuit is used with different components 
for other output powers down to 15 W and for 
4-ohm loudspeaker. Frequency response is 20 
Hz to 50 kHz for -1 dB points. — R. G. Ruehs, 
"15 to 60 Watt Audio Amplifiers Using Comple- 
mentary Darlington Output Transistors," Mo- 
torola, Phoenix, AZ, 1974, AN-483B, p 3. 




7 T 

r 



2500 MF _/ 



<3+V cc 




rO i[( » 



CASCODE AMPUFIER— Uses two sections of 
RCA CA3028A linear IC (U1A is not used). Pro- 
vides power gain of about 40 dB. Unmarked re- 
sistors are on IC. — D. DeMaw, Understanding 
Linear ICs, QST, Feb. 1977, p 19-23. 



* 0+9V 



HIQH OUTPUT CURRENT— Uses CA3094A pro- 
grammable opamp as driver stage for two par- 
allel-connected transistors of CA3183AE array 
to develop 100-mA average AF current (peaks 
up to 300 mA) through 75-ohm load. Diode-con- 
nected transistors D,-D 3 in array provide tem- 
perature compensation for output tran- 
sistors. — "Circuit Ideas for RCA Linear ICs," 
RCA Solid State Division, Somerville, NJ, 1977, 
p11. 



(» ) t vvv — d>- 





R L (ea.75fl) 



f R h 6 l~l^' 

-i- Q 



6 I 

15V 



40 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 10V. 




ERROR TAKEOFF REDUCES DISTORTION— 
Nonlinear distortion is reduced in single-ended 
amplifier by producing voltage proportional to 
distortion and amplifying this error voltage in 
such a way that it can be used to reduce distor- 
tion at output. Circuit uses 741 opamps and 
MJ4000 power Darlington transistors. Tech- 
nique overcomes basic limitation of negative 
feedback wherein feedback loop gain decreases 
as frequency increases. Article also gives vari- 
ation of circuit more suitable for power ampli- 
fier, and describes circuit operation in detail. — 
A. M. Sandman, Reducing Amplifier Distortion, 
Wireless World, Oct. 1974, p 367-371. 




2 ^J 



10 M 



■*— *wv— o- 



o* 



1p 1p 

HI lh 




15n 

-II- 



510M 



0+12V 



-O +350V 




BALANCED OUTPUT WITH OPAMPS— Low- 
cost amplifier provides low-impedance bal- 
anced output from unbalanced signal output of 
preamp. Response is flat from 10 to 20,000 Hz, 
and distortion less than 0. 1 % at 800 Hz into 600- 
ohm load. Gain is 20 dB. Other opamps, such as 
LNI307 or 747 (dual 741) can also be used.— K. 
D. James, Balanced Output Amplifier, Wireless 
World, Dec. 1975, p 576. 



ELECTROSTATIC HEADPHONES— Uses 

LM3900N four-opamp IC and two transistors to 
step up headphone output signal of AF power 
amplifier sufficiently to drive pair of electro- 
static headphones without introducing exces- 
sive distortion. Total harmonic distortion at 1 
kHz is 1% at 300- V peak-to-peak output, and 
drops to 0.1% at 50-V output.— N. Pollock. Elec- 
trostatic Headphone Amplifier, Wireless World, 
July 1976, p 35. 



AUDIO AMPLIFIER CIRCUITS 



41 




O VOUT 



LOW-NOISE TRANSFORMERLESS PREAMP— 
Noise performance of balanced microphone 
preamp is improved with instrumentation am- 
plifier configuration of three opamps. Each half 
of LM387A is wired as noninverting amplifier. 
LM387A serves to amplify low-level signals 
while adding as little noise as possible, leaving 
common-mode rejection for LF356. — "Audio 
Handbook," National Semiconductor, Santa 
Clara. CA, 1977, p 2-37-2-40. 



A, ■ 54dB 
• - METAl FILM 
ADJ. R7FOR VoUT = 0Voc 
«DJ. Ki4 FOR MAX CHIRR 
NOISE -67dB BELOW 
2mV INPUT (-119d!m) 
THD < 0.1X 



5-W CLASS A — Three-transistor feedback loop 
gives excellent DC stability, while arrangement 
of two capacitors and resistor feeding loud- 
speaker keeps these capacitors properly polar- 
ized as AF output voltage swings above and 
below zero level. — R. H. Pearson, Novel 5-Watt 
Class A Amplifier Uses Three-Transistor Feed- 
back Circuit, Wireless World, March 1974, p 18. 



input 1V 
O 



40|1, 
10V 



10)1, 
10V 



150mH 
2R45 



ste 



set for 
900 mA 
i n choke 



I^Tq^ 



M 



-22VO- 



^lh-r ± ll- J 



2m 
25V 



15fl 
5W 



i§ 



2m 
25V 



>R 
>10k 



0.1 nF ? + V CC = H VoltS 



1 . 



a>A/W*--)|-0^ 

1 (iF 



: 005 




10 ,uF 



C3 

100 nF 



^-p-.iu ,xr u. Ul^-p^ 




— 6 



1-W NONINVERTING— Motorola MC1554 IC op- 
erates from single supply and uses capacitive 
coupling to both source and load, for voltage 
gain of 9 with frequency response (-3 dB) from 
200 to 22,000 Hz. Input impedance is 10K, and 
total harmonic distortion is less than 0.75%. 
Use external heatsink. — "The MC1554 One- 
Watt Monolithic Integrated Circuit Power Am- 
plifier," Motorola, Phoenix, AZ, 1972, AN-401, p 
2. 



1-W NONINVERTING WITH SPLIT SUPPLY— 
Motorola MC1554 IC is connected for operation 
from ±7 V to provide voltage gain of 9 over fre- 
quency range (-3 dB) of 40 to 22,000 Hz. Input 
impedance is 10K, and total harmonic distortion 
is less than 0.75%. Use external heatsink. — 
"The MC1554 One-Watt Monolithic Integrated 
Circuit Power Amplifier," Motorola, Phoenix, 
AZ, 1972, AN-401, p 2. 



42 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




O + 12V 




BATTERYLESS MICROPHONE PREAMP— Tran- 
sistor and two components can be mounted in 
microphone housing. R 2 is added to existing 
amplifier to provide operating voltage for 
preamp, while C: feeds preamp signal to input 
of amplifier. — W. H. Jarvis, Line-Powered Mi- 
crophone Pre-Amp, Wireless World, Dec. 1976, 
p43. 



60 W— Combination of National LM391 audio 
driver IC and discrete power transistors pro- 
vides 60-W output for loudspeaker at very low 
distortion. IC output can swing ±40 V. Total har- 
monic distortion of circuit is under 0.05%. — P. 
Franson, Consumer-Product IC's — New Offer- 
ings Trigger an Explosion in Markets Old and 
New, EDN Magazine, Nov. 5, 1977, p 54-65. 



*T»10nF 



SHUTDOWN 




1N4003 




NOTES: 



10k J^ I 3.9k P f" 
I K£/V*-4vVvV I— I 



\\ I 1N4003 

"0.1 (,F - - 




♦— o 



0.22 
5W 
IRC- 
0.001 uf PW5 



27V TO 39V 



IBD350 



25 TURNS 

NO. 22GA. 

MAGNET 

WIRE OR 2-8 ijH 



j" 0.001 n? 0227 T^^ow"" 



i» — ,/vv 1 



47k 




BD351 



-27V TO -39V 

-o 



"HIGH-FREQUENCY GROUND 
"INPUT GROUND 
"•SPEAKER GROUND 



ALL GROUNDS SHOULD BE TIED TOGETHER 
ONLY AT POWER SUPPLY GROUND. 



50°C/W HEAT SINK ON BD348 AND BD349 
3.9°C/W HEAT SINK ON BD350 AND BD351 



' ' I =1-8mA 



c, 
o-ih 



Tr 3 
BCY72 




C107 f^-W^-U^l^j L^ 

06V| lb Tr 2 [ + 06VI Tr, 



| + 06V| 



output 

bias 
currei 
adjust 






c 3 

lOOu 



I-9-3V 
O 



90mA 




DIRECT-COUPLED PUSH-PULL— Provides high- 
quality sound at ample volume for car radio, 
operating from 9.3-V regulated supply. Push- 
pull emitter-follower stages are connected to 
give symmetrical low output impedance on 
both positive and negative portions of audio 
waveform. Input transistor Tr, provides tem- 
perature compensation, while driver Tr 2 pro- 
vides temperature-compensated bias and max- 
imum symmetrical voltage swings to output 
stages. — G. Kalanit, Low Voltage Audio Ampli- 
fier, Wireless World, Oct. 1976, p 74. 



AUDIO AMPLIFIER CIRCUITS 



43 



+9 to 18v. 



560 




FET PREAMP WITH TONE CONTROLS— Devel- 
oped for use with simple 2-W audio amplifier 
when testing very low-level output circuits and 
microphones. Will not load circuit to which 
input is connected. Optional bass/treble tone 
controls are included. — J. SchuKz, An Audio 
Circuit Breadboarder's Delight, CO, Jan. 1978, 
p 42 and 75. 




input up to 50 V 




output 
up to 2A 
O 



3-W DIFFERENTIAL— Upper Motorola MC1554 
power amplifier is connected in standard con- 
figuration for noninverting gain of 9, while 
lower IC has inverting gain of 9 to give effective 
overall voltage gain of 18. Input impedance of 
upper amplifier is 10K while that of lower am- 
plifier is IK, with unequal input coupling capac- 
itors providing required match of frequency re- 
sponses. Differential output connection allows 
output voltage swing to exceed power-supply 
voltage. — "The MC1554 One-Watt Monolithic 
Integrated Circuit Power Amplifier," Motorola, 
Phoenix, AZ, 1972, AN-401, p 4. 



CURRENT CONTROL FOR POWER SWITCH— 
Circuit makes power supply current increase 
gradually from zero when supply is turned on, 
to eliminate transients that sometimes cause 
alarming loudspeaker thumps in audio sys- 
tems. Current through silicon power diode D, is 
controlled by voltage on C,, which charges up 
after closing of switch with time constant 
C,R,R2/(R, + R 2 ). When switch is opened, run- 
down of supply current is controlled by dis- 
charge of C, through R 2 . Article also covers use 
of two current control circuits in tandem for 
handling higher loads. — P. J. Briody, Power 
Supply Delayed Switching, Wireless World, 
March 1975, p 139-141. 



T 



> 



n. 



10-W CLASS A — Highly stable circuit uses eas- 
ily obtainable components. Transistor types are 
not critical. Short-circuit protection is provided 
by constant-current source D,-Tr 2 -Tr 5 -Tr 4 . Out- 
put transistors Tr s and Tr s require heatsinks ca- 
pable of dissipating at least four times rated 
output power. D, and Tr 2 should be in thermal 
contact. — A. H. Calvert, Class A Power Ampli- 
fier, Wireless World, June 1976, p 71. 



input q— II— < 

720mV !' ' 
1 M- 



* 
470 k 




200.U.; 
40V 




"3 
2N697 




HI — o 




*• 2,000,10. 
40 V 

2N2015 



220S 10k « 



X 




Tr 4 
2N2501 



output 



Jo-iA 



-OOV 



j|e adjust to make point X halt the supply voltage (it necessary) 



44 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 35V 




-50V 
(15mA quiescent current) 

CLASS B WITHOUT TAKEOVER DISTORTION— 
Circuit uses two transistor triplets in output 
stage, with quiescent current set at 15 mA by 
Tr 7 which serves as constant-current source. For 
small signals, Tr, and Tr 4 can be regarded as 



long-tailed pair without tail. For positive sig- 
nals, Tr,-Tr 4 become active and behave as super 
emitter-follower, while Tr, with Tr 4 -Tr e serve for 
negative signals. One advantage of circuit is low 
output impedance. — N. M. Visch, A Novel Class 
B Output, Wireless World, April 1975, p 166. 




52 dB 
•-METAL FILM 
NOISE: -MM BELOW 
2mV(-11SdBml 
THD < 0.1% 



15V 



TRANSFORMERLESS BALANCED-INPUT MI- 
CROPHONE PREAMP— Uses FET-input opamp 
to amplify differential signals while rejecting 
common-mode signals. Gain is set at 52 dB by 
ratio of R 3 to R,. Input resistors R, and R 2 are 
made large compared to source impedance 
while being kept as small as possible, for opti- 
mum balance between input loading effects 
and low noise. Good compromise value is 10 
times source impedance for R, -I- R 2 . — "Audio 
Handbook," National Semiconductor, Santa 
Clara, CA, 1977, p 2-37-2-40. 



•40V 







GND- 



10K 



I 



2m 




* Wr 



10K 



22pfd 



-r- 5O0fd 



2200 fX 



o in..2w 



2N6328 or EQUIV 



LOAD 



2N6331 OR EQUIV 



1/V2W 



2// 



"LI— 24 turns, single layer #36 on 10n, 1W res. 

75 W WITH CURRENT LIMITING— Signetics input. IC includes built-in short-circuit protec- stage boost power to 75 W for driving loud- 
NE541 high-voltage power amplifier provides tion, with additional protection provided by ex- speaker load.— "Signetics Analog Data Man- 
current gain of 90 dB from 20 Hz to 20 kHz and ternal current limiting. Transistors in output ual," Signetics, Sunnyvale, CA, 1977, p 765. 
output levels up to 20 VRMS from 300-mVRMS 



AUDIO AMPLIFIER CIRCUITS 



45 



470 

o— Kwvj— 




J — Yf^\- 

-L- 47 l„ 



POWER OPAMPS IN BRIDGE— Bridge configu- 
ration is theoretically capable of 4 times power 
output of conventional quasi-complementary 
or complementary-symmetry amplifier. Use of 
bridge circuit in automotive AM/FM stereo re- 
ceiver requires suitable protection of modules. 



MIC 
INPUT 



OUTPUT 
O 



Article covers incorporation of protective con- 
trols in single module with dual opamps. — E. R. 
Buehler and B. D. Schertz, Fault Protection of 
Monolithic Audio Power Amplifiers in Severe 
Environments, IEEE Transactions on Consumer 
Electronics, Aug. 1977, p 418-423. 




©VOUT 



SINGLE-ENDED MICROPHONE PREAMP— 
Noise performance is -69 dB below 2-mV input 
reference point. Use metal-film resistors for R 2 
and R 5 . Total harmonic distortion is less than 
0.1%. Gain is set by ratio of R4 to R 2 and is 52 
dB. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 2-37-2-40. 




O OUTPUT 



X0.VF 
CERAMIC 



90 W PER CHANNEL— Combination of LM143 
high-voltage opamp and current booster can 
provide up to 90 WRMS into 4-ohm loudspeaker 
or 70 WRMS into 8-ohm loudspeaker. Circuit 
features include short-circuit and overload pro- 
tection along with harmonic distortion below 
0.1% at 1 kHz. Transistors 01-Q4 should be on 
common Thermalloy 6006B or equivalent heat- 
sink. — "Linear Applications, Vol. 2," National 
Semiconductor, Santa Clara, CA, 1976, AN-127, 
p6-7. 



46 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




SPKR 



12 W WITH BOOSTER TRANSISTORS— At sig- 
nal input levels below 20 mW, National LM378 
opamp supplies load directly through 5-ohm re- 
sistor up to current peaks of about 100 mA. 
Above this level, booster transistors are biased 
on by load current through same resistor to in- 
crease output power. Transistors and opamp 
must have adequate heatsinks. — "Audio Hand- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 4-42-4-43. 



HIGH-GAIN JFET— Simpletwo-JFET circuit pro- 
vides gain of 500 at low power. Reducing drain 
current increases gain at sacrifice of input dy- 
namic range. — "FET Databook," National Semi- 
conductor, Santa Clara, CA, 1977, p 6-26-6-36. 



•VinO 




Ay = — = 500 typical 
Yfs 



OS 



INPUT 



~4m 




BRIDGE AMPLIFIER— National LM377 dual 
power amplifier is used in bridge configuration 
to drive floating load that can be loudspeaker, 
servomotor, or other device having impedance 
of 8 or 16 ohms. Maximum output is 4 W at gain 
of 40 dB, with 3-dB response extending from 
about 20 Hz to above 100 kHz. — "Audio Hand- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 4-8-4-20. 



AUDIO AMPLIFIER CIRCUITS 



47 



O +6V 



D40C4 




ERROR ADD-ON REDUCES DISTORTION— 
Based on fact that error at output of upper 
opamp also appears at input of this opamp. 
Error signal is taken from this input for lower 
opamp, where it is amplified by opamp and Dar- 
lington for addition to output of upper Darling- 
ton. Article gives design equations and inti- 
mates that open-loop gain improves at 12 dB 
per octave as compared to conventional 6 dB. 
Applications include reduction of loudspeaker 
distortion which cannot be handled by negative 
feedback. — A. Sandman, Reducing Distortion 
by 'Error Add-On,' Wireless World, Jan. 1973, p 
32. 




5 W WiTH OPAMP— Simple circuit including 
volume control has low harmonic distortion. 
Higher allowable operating voltage of LM384 
opamp gives higher output power, but heatsink 
is required. — "Audio Handbook," National 
Semiconductor, Santa Clara, CA, 1977, p 4-28- 
4-29. 



f 



TREBLE 
12 "BOOST" "CUT" 

f f .. (CW) I5KA (ccw) 



00I 



D|-D 4 IN539I 



"BOOST" IOOKn"CUT" lOKfl 
<CW) qacc (CCW) 



C 2 

0.47 M F 



T "jumper" 




FOR STANDARD INPUT: SHORT C 2 : R, =250 Kil 

C| =0 047 M F; REMOVE R? 
FOR CERAMIC CARTRIDGE INPUT : C| = 00047,,F 

R,=2. 5 MJ1, REMOVE JUMPER FROM C 2 . LEAVE Rj 



12-W OUTPUT — Uses CA3094B programmable nals are mixed in 4:1 ratio. Location of tone con- thermal compensation. — "Circuit Ideas for RCA 

opamp to drive complementary-symmetry trols in feedback network improves signal-to- Linear ICs," RCA Solid State Division, Somer- 

power-output transistors. Intermodulation dis- noise ratio. Hum and noise are typically 700 pV ville, NJ, 1977, p 1 1 . 

tortion is only 0.2% when 60-Hz and 2-kHz sig- (83 dB down) at output. Transistor Q, provides 



48 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Input O — flf- 




* 25V rating necessary it V s can exceed 32V 



4.5-W CLASS B— Milliard TDA2610 drives 15- 
ohm loudspeaker with total harmonic distor- 
tion of less than 1%. Supply is 28 V ± 10%. Net- 
work C2-R1 ensures stability with inductive 
load. — "Audio Power Amplifier TDA2610," Mul- 
lard, London, 1976, Technical Note 35, TP1541. 




8 volts 6 



1-W INVERTING— Uses Motorola MC1554 
power amplifier to provide voltage gain of 35 
with com ponentsshown. Output voltage swing 
is 12 V P-P into 12-ohm load. For response down 
to low audio frequencies (below 100 Hz), large 
value of C is required, such as 1 fiF. Input can be 
direct-coupled at sacrifice in output offset, but 
this can be corrected by properly biasing pin 1 
or terminating it in about 250 ohms. Upper fre- 
quency limit for -3 dB is about 22,000 Hz. — 
'The MCI 554 One-Watt Monolithic Integrated 
Circuit Power Amplifier," Motorola, Phoenix, 
AZ, 1972,AN-401,p3. 



to left hand amplifier 

► 

+ 50V 




to left-hand 
— ► amplifier 



FEED-FORWARD CORRECTION— Circuit re- 
duces distortion caused by nonlinearity of out- 
put power transistors by deriving error com- 
ponent that bypasses these transistors. 
Technique used is known as current dumping. 



Article describes operating principle in detail. 
Circuit shown gives application to commercial 
amplifier (Quad 405), in which midfrequency 
distortion is only about 0.005%. Features in- 
clude elimination of adjustments, alignment 



procedures, and thermal problems during en- 
tire life of amplifier. — P. J. Walker, Current 
Dumping Audio Amplifier, Wireless World, Dec. 
1975, p 560-562. 



AUDIO AMPLIFIER CIRCUITS 



49 




5-W IC — RCA IC includes preamps, power am- 
plifier, and integral heatsink. CA3131 has inter- 
nal feedback network that maintains 48-dB 
gain, while CA3132 requires external feedback 
network including R1 and R2 connected be- 
tween pins 6 and 16. Input 1000-pF capacitor is 
required if input has open circuit. Electrolytic C1 



should be placed as close as possible to pin 10. 
C6 sets 46-dB closed-loop gain point at 200 kHz. 
C7 equalizes gain for positive and negative sig- 
nal swings. C9 sets low-frequency response of 
amplifier. Recommended supply voltage is 24 
VDC. — E. Noll, Audio-Power Integrated Cir- 
cuits, Ham Radio, Jan. 1976, p 64-66. 



L3£> 




LOW-NOISE OPAMP PREAMP— Circuit com- 
bines noise features of discrete design with sim- 
plicity and high open-loop of IC opamp such as 
741. Transistors can be 2N3708, BC109, or 
equivalent. Output impedance is low enough to 
drive headphones directly. — D. R. Hedgeland, 
Op-Amp Pre-Amp, Wireless World, Dec. 1972, 
p575. 



6.8k •* — ^ 








50 mW FLAT TO 30 kHz— Power amplifier 
achieves push-pull output with single transis- 
tor. Both transistors should be germanium such 
as 2IM404. SK3004, or HEP-253— Circuits, 73 
Magazine, Feb. 1974, p 100. 



PREAMP IN MIKE— Common-source FET 
preamp and 15-V battery fit into Turner 350C 
hand mike for boosting output of ceramic ele- 
ment 20 dB. Frequency response of preamp is 



flat from 200 Hz to over 1 00 kHz. Drain is 200 pA 
only when push-to-talk is pressed, giving long 
battery life. — G. Hinkle, Self-Powered Mike 
Preamp, 73 Magazine, Nov. 1976, p 65. 




IMPEDANCE BUFFER— Complementary-tran- 
sistor output stage provides required low 
impedance for driving headphones from 
SN72310 voltage-follower opamp. Supply is 



±12 V. — "The Linear and Interface Circuits Data 
Book for Design Engineers," Texas Instruments, 
Dallas, TX, 1973, p 4-41. 




ULTRALOW-NOISE PREAMP— Provides gain of 
1000 over bandwidth of 20 Hz to 10 kHz, oper- 
ating from 24-V supply and 600-ohm source 
impedance. Design procedure is given. Total 
wideband noise voltage is 43.7 /iV, and wide- 
band noise figure is 2.83 dB. — "Audio Hand- 
book," National Semiconductor,. Santa Clara, 
CA, 1977, p 2-15-2-19. 



50 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




BRIDGE AMPLIFIER — Two opamps are used in 
bridge configuration to provide twice the volt- 
age swing across loudspeaker load for given 18- 
V supply, increasing power capability to about 
twice that of single amplifier. To eliminate ex- 
cessive quiescent DC voltage across load, non- 
polarized capacitor can be used in series with 
load or 1-megohm pot can be connected be- 
tween pins 1 of opamps with position of moving 
arm adjusted to balance offset voltage. Com- 
ponents shown with dashed lines are added for 
stability with high-current load. — "Audio Hand- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 4-21-4-28. 



BASS BOOST — Compensates for poor bass re- 
sponse of loudspeaker by use of external series 
RC circuit between pins 1 and 5, paralleling in- 
ternal 1 5K resistor of opamp. 6-dB effective bass 
boost is obtained if resistor is 15K, and lowest 
value for stable operation is 1 0K if pin 8 is left 
open. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 4-30-4-33. 




input 50V 




CURRENT-CONTROLLED SWITCHING— Addi- 
tion of current control to 40-V regulated power 
supply for audio amplifier eliminates switch-on 
transients that sometimes cause alarming loud- 
speaker thumps. Switch S, which can be either 
relay or third pole on standard ON/OFF switch 



of amplifier, is opened to initiate charging of 
800-fiF capacitor that allows gradual buildup of 
output current. Similar transient suppression 
occurs when switch is closed to initiate current 
run-down as set is turned off. Run-up and run- 



down times are a few seconds each. Article also 
gives simpler current control circuit suitable for 
use with unregulated supplies. — P. J. Briody, 
Power Supply Delayed Switching, Wireless 
World, March 1975, p 139-141. 



AUDIO AMPLIFIER CIRCUITS 



51 



MIC 
INPUT 




VQUT 



=■ c c 




™«r? 



100k 



INVERTING AC AMPLIFIER— Provides gain of 40 
dB when using 24-V supply and input imped- 
ance greater than 10K. Low-frequency perfor- 
mance is flat to 20 Hz. Design procedure is 
given. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA,"I977, p 2-20-2-24. 



BALANCED-INPUT MICROPHONE PREAMP— 
Use of two wires for microphone signal and 
separate wire for ground keeps hum and noise 
at minimum. Signal wires are twisted together 
in shield acting as ground. Net gain is 52 dB, 



giving 0-dBm output for nominal 2-mV input. 
Noise performance is -86 dB below 2-mV input 
level, and rejection of common-mode signals is 
60 dB. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 2-37-2-40. 




-200V 



TWO-TUBE WILLIAMSON OUTPUT— Response 
is flat from 10 Hz to over 50 kHz for outputs up 
to 15 W, and total harmonic distortion for full 
power output at 15 kHz is only 0.25%. Output 



stage uses tubes connected as triodes in push- 
pull. Input transistor can be any in Philips 
BFQ10-16 family or equivalent replacement 
such as Siliconix E401. Article gives many suit- 



able replacements for other transistors as well, 
and describes design of required feedback cir- 
cuits in detail. — S. Bergkind, Transistor Driver 
for Valve Amplifiers, Wireless World, April 1976, 
p 36-40. 



CHAPTER 4 

Audio Control Circuits 



Includes variety of tone controls, compressor, expander, compandor, clipper, 
mixer, clamp, automatic level control, click suppressor, attenuator, equalizer, 
speech filter, noise squelch, logic-controlled gain, voice- or tone-controlled 
relays, active crossover, and switching gate circuits for audio signals. See also 
Audio Amplifier, Filter, Receiver, and Stereo chapters. 




COMPRESSOR 

OOUT 



HI-FI COMPRESSOR— One section of Signetics 
NE570 dual compandor is used with external 
opamp for compression of large input signals in 
high-fidelity audio system. To prevent overload 
by sudden loud signal when compressor is op- 
erating at high gain for small signals, brute- 

52 



force clamp diodes D 3 and D 4 limit output 
swings to about 7 V P-P. Limiting action pre- 
vents overloading of succeeding circuit such as 
tape recorder. Circuit includes input compen- 
sation network required for stability. Corre- 



sponding expander used for playback of re- 
corded material should have same value for 
rectifier capacitor C,, as is used in compressor. — 
"Signetics Analog Data Manual," Signetics, 
Sunnyvale, CA, 1977, p 804. 



AUDIO CONTROL CIRCUITS 



53 




2 FERRITE 
BEADS I^F 

(SEE TEXT) 



PREEMPHASIS AT 1500 Hz— Single-transistor 
peaking filter is combined with low-noise RF- 
protected preamp stage to improve speech in- 
telligibility for any type of modulation. Effec- 
tiveness is most noticeable with deep bass 
voice, where soft peak around 1500-2000 Hz 
improves speech intelligibility. Can also serve 
as audio-type CW or SSB filter. — You Can 
Sound Better with Speech Pre-Emphasis, 73 
Magazine, Feb. 1977, p 42-43. 



^250 M F 



R-l 39k 



-AA/V- 



R28< 

100k< 



Vs777 



control 

voitage 



C 3 , 

100n' 



Cl. 

10' 



"4? "1 I 



Ca-i- >R 3 




»Rl4 
*270k 



nsV 



OV 
-15V 



source- 
tollower 



7>* Co + -J- SET ATTACK 



yfc- 





IC2 



-M- 

D 3 

IS44 



D, 
1S44 



-15V 
quiescent + 0-26V 






15V 



IS44 ' 




-15V 



sound studios. Output-sensing amplifier using from 1000 ohms to infinity, using either 
IC, has gain of 19 over audio band. Tr 2 stage is switched or variable components. Article de- 
COMPRESSOR/LIMITER— High-fidelity circuit phase-splitter driving precision rectifiers IC 2 and scribes circuit operation and adjustment in de- 
uses voltage-controlled attenuator to increase IC 3 . Final part of circuit defines attenuation time tail. Tr 6 is BC184L or equivalent.— D. R. Self, 
attenuation of input signal in response to volt- constants; R 28 sets attack time and R 27 decay High-Quality Compressor/Limiter, Wireless 
age of control loop. Designed for use in modern time. R 26 can range from to 1 megohm and R 27 World, Dec. 1975, p 587-590. 




54 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CONSTANT AF LEVEL— Provides constant out- 
put level even though input may vary between 
50 m V and 6 V, for distribution to tone decoders 
of autocall system used to monitor simplex or 
repeater channel to which amateur radio re- 
ceiver is tuned. Positive terminal of electrolytic 
C3 must go to pin 6 of 741.— C. W. Andreasen, 
Autocall "76, 73 Magazine, June 1976, p 52-54. 



vl' TO TONE DECODERS 



playback . 
input {& 



SWITCH POSITIONS 
compress 




^T\ output to 
"^J recorder 



Output 



1N914 lOOn 1N914 




COMPANDER WITH 100-dB RANGE— Simple 
square-law circuit preserves dynamic range of 
virtually any input signal when recorded by or- 
dinary tape recorder. Suitable for speech sig- 
nals as well as for recording or playback in noisy 
environments. Opamp A, should have sepa- 
rately decoupled supply. Switching provides 
compression during recording and expansion 
during playback. Tracking of photocells is es- 



sential for accurate power-law compansion. 
LED can be glued with clear epoxy to matched 
photocells. Use silicon signal diodes such as 
1N914, 1N4148, or 1S44. Inexpensive photocells 
such as Vactec VT-833 gave suitably low dis- 
tortion. Article gives performance characteris- 
tics and operating details.— J. Vanderkooy, 
Wideband Compander Design, Wireless World, 
July 1976, p 45-49. 



Ri 



39k 
-WV OA 



5k linear w.w. 



I s^^ = ^ ma * 



8k2 



-AAA/— OB 
39k 



PANNING MIXER POT— Circuit gives best pos- 
sible approach to sine law so A 2 = B* is constant 
for all positions of wiper. Calculated error is less 
than 1 dB over full range of wiper. Use wire- 
wound potto minimize crosstalk. — J. Dawson, 
Single Gang Pan-Pot, Wireless World, Feb. 
1976, p 78. 



+ SV 




AUDIO SWITCHING GATE— Can be used with 
programmed channel selectors, as required in 
music synthesis for controlling audio signals by 
means of TTL levels. DC offset at output is neg- 
ligible when gate is off, simplifying design of 
subsequent stages. Use logic 1 (+5 V) to open 
gate, and logic (0 V) to close it.— L. Cook, An- 
alogue Gate with No Offset, Wireless World, 
Feb. 1975, p 93. 



AUDIO CONTROL CIRCUITS 



55 




CLIPPER — Provides speech clipping at RF level 
for SSB transmitters. Based on use of two Am- 
perex 455-kHz IF crystal filters having 4-kHz 
rated bandwidth, in place of costly conventional 
sideband filters. Miller 8902-B IF amplifier mod- 
ule simplifies wiring. Diode balanced modulator 
at upper left can use individual 1N63 or 1N914 
diodes, or RCA CA-3019 hex diode array that 
also provides diodes for RF clipper. Audio input 
can be taken from speech compressor of re- 
ceiver, or separate audio amplifier can be added 
to boost AF level. Same diode types are used in 
product detector for final SSB signal, lower 
right, which is diode ring demodulator taking 
injection voltage from carrier oscillator. Article 
tells how pin 8 on IF module (not connected in- 
ternally) is bridged to solder line between link 
output of last IF transformer and AM detector 
diode, and gives other construction details. — J. 
J. Schultz, Inexpensive RF Speech Clipper, 73 
Magazine, Sept. 1974, p 61-64 and 66. 

+20V 



e, O 




LINEAR 1 :4 VOLUME EXPANDER— Gain varies 
automatically with strength of input signal, 
being lowest for weak signals. Resistors R3 and 
R4 modify linear control curve to give log curve 
desired for audio systems. Overall gain of circuit 
is about dB at midrange of expansion. Lower 
pair of LM324 quad opamp sections function as 
full-wave precision linear peak detector. For 
stereo, only upper part of circuit needs to be 
duplicated for second channel. — "Linear Appli- 
cations, Vol. 2," National Semiconductor, Santa 
Clara, CA, 1976, AN-129, p 7. 



SET TO (10V 



56 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




EXPANDER— Uses Signetics dual-channel com- 
pandor IC; 571 has lower inherent distortion 
and higher supply voltage range (6-24 V) than 
571 (6-18 V). Values shown are for 15-V supply 
with either IC. Gain through expander is 1.43 
Vi N . where V IN is average input voltage. Unity 
gain occurs at RMS input level of 0.775 V, or 
dBm in 600-ohm systems. — W. G. Jung, Gain 
Control IC for Audio Signal Processing, Ham 
Radio, July 1977, p 47-53. 



SWITCHING-CLICK SUPPRESSOR— Correction 
network shown can be inserted in audio chan- 
nel of mixing console without producing tran- 
sients or level changes. Although Baxandall net- 
work is shown, switching technique is 
applicable to other filters. With S 1 normally 
open and S 2 normally closed, circuit operation 
is normal. If switch positions are simultane- 
ously reversed, response remains flat regard- 
less of positions of bass and treble pots, center- 
frequency gain remains unchanged, and phase 
shift is unchanged. There is then no transient 
interruption of AF signals. Switching clicks can- 
not occur because there is no direct current in 
the network.— J. S. Wilson, Click-Free Switch- 
ing for Audio Filters, Wireless World, Jan. 1975, 
P12. 




10n S2k 

TREBLE 



FULL-WAVE RECTIFIER 




SPEECH PROCESSOR— Can improve signal 
strength and intelligibility of voice signals up to 
6 dB without unpleasant changes in fidelity. 
Used between microphone and input of AM or 
SSB transmitter. Based on separation of signal 
envelope from constant-amplitude carrier that 
together make up voice signal. After logamp U6 
separates components of speech waveform, en- 



velope is filtered out by active RC high-pass fil- 
ter U8 having 50-Hz cutoff, with exactly unity 
gain above cutoff. Filtered signal goes to ex- 
ponential amplifier U9-U10 and is then multi- 
plied by correct sign information in U14. Sign 
information is obtained by hard-limiting input 
voice signal with diode clipper CR5-CR6. Re- 
sulting square-wave output is multiplied by sig- 
nal from UJT in U14. Processed signal goes to 



transmitter input through low-pass filter U12 
having sharp cutoff above 3 kHz to eliminate 
unwanted high-frequency energy. CR1-CR4 are 
1N914 or other matched silicon diodes. T1 is 
250-mW audio transformer. Article gives con- 
struction and adjustment details.— J. E. Kauf- 
mann and G. E. Kopec, A Homomorphic Speech 
Compressor, QST, March 1976, p 33-37. 



AUDIO CONTROL CIRCUITS 



57 




COMPRESSOR/LIMITER— Developed for use 
with microphone in public-address systems. 
Bandwidth is 15 Hz to 25 kHz. R, sets threshold 
voltage and compression law. Output of 
CA3130 inverting opamp is made as large as 
possible before being applied to rectifier and 
low-pass filter, to minimize effects of diode non- 
linearities and capacitor leakage. Low-pass fil- 
ter gives required fast attack time of about 500 
ps and long decay time of about 1 min. — M. B. 
Taylor, Speech Compressor/Limiter, Wireless 
World, May 1977, p 80. 



THREE-INPUT MIXER— Motorola MC3401P or 
National LM3900 quad opamp serves for three 
input amplifiers each having adjustable gain 
range of 1 to about 11 and input impedance 
above about 100,000 ohms. Common outputs 
feed fourth opamp section connected as high- 
impedance amplifier. Maximum overall gain for 
mixer-amplifier is about 300. Use well-filtered 
9-15 V supply or battery capable of supplying 
25 mA. — C. D. Rakes, "Integrated Circuit Proj- 
ects," Howard W. Sams, Indianapolis, IN, 1975, 
p 21-22. 




Vpos o 



AUDIO 
INPUTS 
MOV MAX) 



l-IO — \w- 
20K£! 



DIGITAL 
INPUT ~ 



7T, — -<n 

R1 f o.i^f -L 





LIKE VALUED 
PAIRS MATCHED 
R1 TO R2 
R3TO R4 
R5 TO RG 



AUDIO 
OUTPUT 
I 10V MAX) 



•APPROPRIATE AMPLIFIERS 
OP-01 HIGHEST PERFORMANCE 
OP-09.OP 11 BEST GENERAL PURPOSE 



CLICKLESS LEVEL-CONTROL ATTENUATOR— 
Uses two Precision Monolfthics DAC-76 D/A 
converters to eliminate gain-change transients 
while providing exponential control of audio 
signal level. Maximum (all 1s) gain is unity from 
either input to output, while differential input 
to output gain is +6 dB. Control range is 78 
dB. — W. Jung and W. Ritmanich, "Audio Appli- 
cations for the DAC-76 Companding D(A Con- 
verter," Precision Monolithics, Santa Clara, CA, 
1977. AN-28, p 4. 



58 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



INPUT O- 



0.7V TO 7V RMS| 
30 Hz 
TO 
50 kHz 



AD533J > 

DIVIDER 
CONNECTION.. 
X / 



AVE RAGE. AC OUTPUT 
= 7V RMS±1% 

— o 



33k 



2.2 liF 

-K- 



2.2 ^F 



100k 



1N4148 ^/l. , h 

■"M - "^ AD74K 



^ INTEGRATOR - RECTIFIER 



AF LEVEL CONTROL— AD533J analog multi- 
plier used in its divide mode provides measure 
of automatic level control to compensate for 
variations in loudness occurring from micro- 
phone to microphone in public-address system. 
Divider output is first rectified and compared 
with -15 V reference. Difference is then inte- 
grated and fed into denominator of divider-con- 
nected AD533J as control signal V*. Average AC 
output is held within 1% of 7 V. — R. Frantz, An- 
alog Multipliers — New IC Versions Manipulate 
Real-World Phenomena with Ease, EDN Maga- 
zine. Sept. 5, 1977, p 125-129. 




1 ALL RESISTORS '/.W.!5% 

2 POTS ARE LINEAR TAPER 
3. LM349: Vcc * *15V (PIN 41, 

V£E = -15V(PIN11)0EC0UPIE0 
WITH 01 »f CAPS 
4 CAP TOLERANCE i10% 



fo (Hz) 


C1 


32 


0.022/jF 


64 


0.01 1/jF 


125 


0.0056 aiF 


250 


0.0027/jF 


500 


0.001 5/jF 


1k 


680 pF 


2k 


330 pF 


4k 


160pF 


8k 


82 pF 


16k 


43 pF 



ROOM EQUALIZER— Ten-octave equalizer is 
combined with pink-noise generator in such a 
way that all but one octave band can be 
switched out, with pink noise passed through 
remaining filter to power amplifier and loud- 
speaker. Microphone with flat frequency re- 
sponse over audio band is used to pick up re- 



sulting noise at some center listening point in 
room being equalized. Amplified output of mi- 
crophone drives VU meter where arbitrary level 
is established for one filter section. Other filter 
sections are then switched in one at a time and 
adjusted to give same VU reading. Equalizer 
settings then give flat room response for all ten 



octaves. High end can then be rolled off or low 
end boosted to suit personal preference. Ad- 
justments are readily repeated when furniture 
is changed in room. Table gives values of C, for 
each octave. — "Audio Handbook," National 
Semiconductor, Santa Clara, CA, 1977, p 2-53- 
2-59. 



AUDIO CONTROL CIRCUITS 



59 




COMPRESSOR— Circuit has unity gain at 0.775 
VRMS input and complementary input/output 
characteristic. Voltage gain through compres- 
sor is square root of 0.7/V, N , where V IN is average 
input voltage. Uses Signetics dual-channel 
compandor IC; 571 has lower inherent distor- 
tion and higher supply voltage range (6-24 V) 
than 571 (6-18 V).— W. G. Jung, Gain Control IC 
for Audio Signal Processing, Ham Radio, July 
1977, p 47-53. 



CONSTANT 1 .8-V AF FOR SSB— Uses Motorola 
MFC6040 voltage-controlled amplifier IC having 
13-dB gainjmd maximum of 90-dB gain reduc- 
tion. Q1-Q2 form microphone preamp, Q4 is 
AGC detector/amplifier for IC, and Q3 is output 
buffer. With 500-ohm dynamic microphone, 
output remains constant at 1.8 VRMS. — L. No- 
votny. Speech Compressor, Ham Radio, Feb. 
1976, p 70-71. 



MICROPHONE' 




">i" r /h 



(HEP SOOISI 






"OH 



ASYMMETRICAL ACTIVE CROSSOVER— High- 
pass and low-pass active filters using National 
LF356 opamps are asymmetrical about 500-Hz 
crossover point. Sum of filter output voltages 
is always constant and equal to unity. Rolloff of 
low-pass filter is only -6 dB per octave, as com- 
pared to -18 dB per octave for high-pass fil- 
ter. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 5-1-5-7. 



> MISMATCH BETWEEN Rs ANO Rg CORRECTS 
FOR GAIN ERROR OF HIGH PASS OUE TO 
CAPACITOR TOLERANCES. 



«0L 



60 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



FOR SINGLE SUPPLY 
+ 30 V 
2 2 Mil 




20 dB FLAT POSITION GAIN 

±15 dB BASS AND TREBLE BOOST AND 

CUT AT 100 Hz AND 10 kHz, RESPECTIVELY 

25 VOLTS p-p OUTPUT AT 20 kHz 

-3 dB AT 24 kHz FROM I kHz REFERENCE 



TREBLE 



CUT 



200 kfl 
0012 fit (LINEAR) 0.001 pF 

II — T— T VVW II 

- ±100 pF 



18 kI2< 



TlOO pF T 



0022 /if 
2mF T 
=-)F^wi- 



fT^Tc 



J00022 ,ir 



X* 



FOR DUAL SUPPLIES 
+ 15 V 



10 kil I Mfi 100 kSl 

BOOST CCW (LOG) CUT 
BASS 

TONE CONTROL NETWORK 




TONE CONTROL NETWORK 



BASS/TREBLE BOOST/CUT— Using linear and 
log pots with tone control network in feedback 
path of CA3140 bipolar MOS opamp, circuit pro- 
vides 20-dB gain in flat position and ± 1 5 dB bass 
and treble boost and cut at 100 and 10,000 Hz. 
Output is 25 V P-P at 20 kHz and is -3 dB at 24 
kHz from 1-kHz reference. Optional connection 
for ±15 V supply is also shown. — "Circuit Ideas 
for RCA Linear ICs," RCA Solid State Division, 
Somerville, NJ, 1977, p 10. 



HIGH-ON LOGIC CONTROL— Uses Signetics 
NE571 or NE570 analog compandor. When con- 
trol input is high, CR1 is off and current devel- 
oped by Rsain flows into rectifier input, allowing 
audio to be amplified. Gain is unity (or other 
nominal value chosen by changing value of R3) 
for control inputs greater than 3 V. Switching is 
abrupt, with full attenuation below 1.5 V. Nar- 
row transition width and nominal DC center of 
1 .8 V allow direct control from CMOS, TTL, DTL, 
or other positive logic. Supply voltage should 
be stable. — W. G. Jung, Gain Control IC for 
Audio Signal Processing, Ham Radio. July 1977, 
p 47-53. 



;qijjf JT 



3V RMS 
AUDIO 
CONTROL INPUT 

INPUT 



1 



— C RECT 
0.4 ?i,F 



Ai 




+ I5V 
o 



AG IN 3 



cm 



04) 



RECT IN 2 



571 




C2 



IOiiF 



Ih 



13 V+ 



< /6J C RECT 



- C RECT 
v 047pF 



rh 



5 (-)IN 




02) T 




R3$ -■ 
82k > s~ 


L-C3 

"^ 100 


7 OUT ) 




(10) 






' R4 
> 100 



R6 

100k 

— vw- 



>F 



!> OUTPUT i 



LOW-ON LOGIC CONTROL— Uses Signetics 
NE571 or NE570 analog compandor. Gain is de- 
termined by current developed through R GA | N in 
conjunction with internal 1.8-V voltage refer- 
ence. When control input is low, normal current 
flows through R^^. When control signal is high, 
CR1 is forward-biased, interrupting current 
flow, and output is attenuated. — W. G. Jung, 
Gain Control IC for Audio Signal Processing, 
Ham Radio, July 1977, p 47-53. 



AUDIO CONTROL CIRCUITS 



61 



1uF 10K 100K 

INPUT O 1| • W\ • \W- 



0033 U F 




OUTPUT 
05V 

PEAK TO PEAK 



TONE CONTROL FOR OPAMP— Provides up to dBoftrebleboostorcutat20kHz.Turnoverfre- "Signetics Analog Data Manual," Signetics, 
20 dB of bass boost or cut at 20 Hz and up to 19 quency is 1 kHz. Opamp can be 531 or 301. — Sunnyvale, CA, 1977, p 638-640. 



SPEECH FILTER— High-pass and low-pass fil- 
ters in cascade provide corner frequencies of 
300 and 3000 Hz for limiting audio bandwidth to 
speech frequencies. Rolloff beyond corners is 
-40 dB per decade. Input-to-output gain is 1. — 
"Audio Handbook," National Semiconductor, 
Santa Clara, CA, 1977, p 2-49-2-52. 



vmO-|{-H 





,, "10 R 30 

i Ht-^vVv-i <-VvV 

270k 130k 



Input f> 




IMPROVED BAXANDALL CONTROL— Uses sep- 
arate "effect" controls for bass and treble to 
limit maximum degree of boost and cut obtain- 
able from bass and treble controls. R„ controls 



effect for bass and R 2 , for treble. Circuit has 
unity gain with controls set flat. Article gives 
response curves and describes operation of cir- 



cuit in detail. — M. V. Thomas, Baxandall Tone 
Control Revisited, Wireless World, Sept. 1974, 
p 341-343. 



62 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



10 UF 



f 



DYNAMIC 
MICROPHONE 



© 





0.1 nF 



0.1 UF 



-\Xa<V-A- 



AUDIO 
OUTPUT 



VOX WITH SPEECH COMPRESSION— Turns on 
transmitter automatically when operator be- 
gins speaking into microphone. Circuit 
switches back to receiving condition automat- 
ically at end of message. IC can be LS370 or 
equivalent such as LM370 or SC370. Amount of 
compression is adjusted with 10K pot, for re- 
ducing gain of IC automatically to maintain rea- 
sonably constant audio output at pin 8 despite 
different voice levels at microphone. — E. M. 
Noll, "Linear IC Principles, Experiments, and 
Projects," Howard W. Sams, Indianapolis, IN, 
1974, p 344-347. 



<?— )b 



COMPRESSOR— Keeps output voltage con- 
stant as long as input signal is kept above AF 
threshold level. Opamp is MC3340P. — Circuits, 
73 Magazine, Holiday issue 1976, p 170. 



C2 
47>iF 



"'° eC O/ 



22 M F 



*3 

Bcioac 



IO M F 



SPST TOGGLE 



200/.F 



RESISTORS -MINIATURE I/4W. 5 OR 10% 
CI.C5.C6.C7-ELECTR0LYTIC ,16V WKG 
C3- ELECTROLYTIC. 23V WKG 
C8- ELECTROLYTIC , 6V WKG 
C2-TYPE C260(MULLARD) 



INPUT LOW-PASS FILTER 



C3 
0.1 |iF 10% 



CVSD ENCODER 



U3 
PIN 4 



Ul. U2, U3. HARRIS HA-4741 QUAD OP AMP 

CAPACITORS IN pF UNLESS OTHERWISE 

STATED 

RESISTORS 1/20 WATT 

CAP. TOL. 1% UNLESS OTHERWISE 




CVSD DECODER 
AUDIO OUT 



CVSD ENCODER 
AUDIO OUT 
FOR SIDETONE 



^-hl 



AUDIO FILTERS FOR SNR MEASUREMENT— 
Used in checking performance of Harris HC- 
55516/55532 half-duplex modulator-demodula- 
tor systems for converting voice signals into se- 
rial NRZ digital data and reconverting that data 



back to voice. Supply required for opamp sec- 
tions is ± 15 V. Response of input filter is down 
3 dB at 3 kHz and is down 20 dB at 9 kHz. Re- 
sponse of output filter is flat up to 3 kHz and 



C17 VOICE OU1 

4.7 »F 10V 10% 

down more than 45 dB from 3.8 kHz to 100 
kHz. — "Linear & Data Acquisition Products," 
Harris Semiconductor, Melbourne, FL, Vol. 1, 
1977, p 5-10. 



AUDIO CONTROL CIRCUITS 



63 




SOUND-OPERATED RELAY— Output of about 
1 .8 mVRMS from crystal or ceramic microphone 
will energize relay when sensitivity control R4 
is at maximum. First two stages form high-gain 
RC-coupled AF amplifier, output of which is rec- 
tified by silicon diode X1 . DC voltage developed 
across diode is applied to gate of Siliconix U183 
FET which acts as DC amplifier driving Sigma SF 
or equivalent relay. To adjust, short microphone 
terminals, set R4 for maximum sensitivity, then 
adjust R10 until relay opens. — R. P. Turner, "FET 
Circuits," Howard W. Sams, Indianapolis, IN, 
1977,2nd Ed., pi 11-1 13. 



SYMMETRICAL ACTIVE CROSSOVER— Pro- 
vides -18 dB per octave rolloff (third order) and 
maximally flat (Butterworth) characteristics for 
crossover frequency of 500 Hz. Uses National 
LF356 opamps in high-pass and low-pass filters 
and same opamp as buffer having low driving 
impedance required by active filters. Power 
supplies are ±15 V. Design equations are 
given. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 5-1-5-7. 




< c • SCO Hi 
GAIN = QdfiV 



+ 15V -15V 

9 9 



13 I 1 ' , , I 



>20k 
1 mF > f- 

y— </VN A • 

X 30k |_ 

V,n O " — - H> a in j 

0.4V(ppXV |N <6V(p-p| 5l |6 JlO 



V OUT =3V(p-pl±2% 

O 





1.6 kfi. 



3.9 kfi 



Q 3 J-- 

. i 1, 1 



WIDEBAND AF LEVEL CONTROL— AD531 ana- 
log multiplier can hold output to 3 V P-P ± 2% 
for inputs from 0.4 to 6 V P-P, at frequencies 
from 30 Hz to 400 kHz. Opamp type is not criti- 
cal. — R. Frantz, Analog Multipliers — New IC 
Versions Manipulate Real-World Phenomena 
with Ease, EDN Magazine, Sept. 5, 1977, p 125- 
129. 



Qi - Q 5 : RCA CA3045 

THUMPLESS CONTROL— Five-transistor circuit 
for audio amplifier applications eliminates 
thumping sounds that can sometimes be heard 
when level of input signal changes suddenly. 
Differential amplifier Q,-Q 2 , with R, in emitter- 
current control circuit, eliminates thump. Con- 
trol input acts on identical transistors Q 3 -Q 4 
which make transconductance of differential 
pair Q,-Q 2 vary in direct proportion to control 
voltage. Fifth transistor in array, 0*. is used as 
output signal buffer. Amplifier gain is 30 for con- 
trol voltage of 15 V. — P. Brokaw, Automatic 
Gain Control Quells Amplifier Thump, Electron- 
ics, Jan. 10, 1974, p 131-132; reprinted in "Cir- 
cuits for Electronics Engineers," Electronics, 
1977, p 46-47. 



64 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



cv ^-r 



2-8 OHM 
OUTPUT 



MALE-FEMALE VOICE SWITCH— Circuit devel- 
oped by NASA engineers to improve intelligi- 
bility of voice communication during Apollo 
moon shots passes only the three portions of 
the speech spectrum required for clear speech: 
300-400 Hz and 2500-3000 Hz for both sexes 
and 900-1700 Hz for males or 1100-1900 Hz for 
females. Pot adjusts null to about 600 Hz. Circuit 
improves readability of weak DX voice signals 
in noise. — J. Fisk, Circuits and Techniques, Ham 
Radio, June 1976, p 48-52. 




INPUT 

6 FROM A 

ALC 



° OUTPUT ° 



SPEECH FILTER— Pair of Bessel-type high-pass 
filters removes undesired components created 
by peak clipping during audio signal processing. 
Developed for use with automatic level control 
applications of NE571 analog compandor. — W. 
G. Jung, Gain Control IC for Audio Signal Pro- 
cessing, Ham Radio, July 1977, p 47-53. 



TWO-CHANNEL PANNING— Provides smooth 
and accurate panoramic control of apparent 
microphone position between two output 
channels, as often required in mixing consoles 
at recording studios. Requires only single linear 
pot. At each extreme of pot, gain is unity for one 
channel and zero for other. With pot centered, 
gains for both channels are -3 dB. R 2 depends 
on supply voltage used, which can be from 9 to 
30 V. — "Audio Handbook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 2-59-2-61. 




CHANNEL t OUT 



CHANNEL 2 OUT 



+Vfcc 12 V 




CASCODE TONE CONTROL— Circuit raises 100- 
mV input signal level to 1 V for driving power 
amplifier and uses cascode arrangement to im- 
prove S/N ratio of tone control network. Values 



shown give maximum bass boost or cut at 50 
Hz with R ls and maximum treble boost or cut at 
10 kHz with R 20 . Tr 2 can be BC15, BC214, BC309, 
or equivalent. Other transistors can be BC109, 



BC114, BC184, or equivalent.— J. N. Ellis, High 
Quality Tone Control, Wireless World, Aug. 
1973, p 378. 



AUDIO CONTROL CIRCUITS 



65 




t. ALL RESISTORS 'AW. 5%. 

2. POTS ARE LINEAR TAPER. 

3. PIN 4 CONNECTED TO V(X = *15V; 
PIN 11 CONNECTED TO VfE * -15V; 
DECOUPLED WITH O.lnF CAPS AT 
EACHQUAOOPAMP. 

4. CAP TOLERANCE i10%. 



(DUPLICATE ABOVE FOR 
A TOTAL OF 10 CIRCUITS, 
SUBSTITUTIMG APPROPRIATE 
CAP VALUES FROM TABLE 

in. VI 










14 equalize! 


ikHi 


_H 






2kHi 


~ 








fo (Hi) 


Cl 


c 2 


4kH* 


32 


J.18jiF 


0.018juF 


SkHi 


64 


3.1»F 


0.01*iF 




125 


3.047jiF 


00047/jF 




250 


3.022/iF 


0.0022(1* 


16kHz 


500 


3.012*iF 


0.0012mF 




1k 


3.0056 jiF 


560pF 




2k 


3.0027pF 


270pF 




4k 


3.001 5/iF 


IBOpF 




8k 


380pF 


68pF 




16k 


240pF 


24pF 



OCTAVE EQUALIZER— Provides ten bands of 
tone control, separated by one octave in fre- 
quency, with independent adjustment for each. 
Used to compensate for unwanted amplitude- 
frequency or phase-frequency characteristics of 
audio systems. Values of C, and C s for each cir- 
cuit are given in table. With control R 2 In flat po- 
sition, circuit becomes all-pass with unity gain. 
Moving R 2 to full boost gives bandpass charac- 
teristic, and moving in other direction to full cut 
gives band-reject or notch fitter. For stereo, 
identical equalizer is needed for other 
channel. — "Audio Handbook," National Semi- 
conductor, Santa Clara, CA, 1977, p 2-53-2-59. 



AUTOMATIC LEVEL CONTROL— Uses Signet- 
ics NE570 or NE571 analog compandor to pro- 
vide automatic level control for audio signal 
processing, to give constant high percentage 
modulation despite varying input levels. Op- 
tional resistor R x varies threshold of level reg- 
ulation. Widest range of gain control is obtained 
with R x open. When resistor value is lowered, 
larger input signal is required for full output. 
Peak-level clipping with pair of reverse paral- 
leled LEDs controls overshoots on speech by 
limiting RMS output to 2.2 V P-P. R r regulates 
clipped amplitude. — W. G. Jung, Gain Control 
IC for Audio Signal Processing, Ham Radio, July 
1977, p 47-53. 



-^F 






777 io«r 






1161 C BECI 



T LEO 1,2 W 
^ MLEPS.5 ^ 



rnr~t h 

OOUTPUTO 



7^ 



INPUT 



H 



0.01 »f 



TONE CONTROL WITH HIGH INPUT IMPED- 
ANCE— Use of 2N5458 JFET ahead of opamp 
feedback-type tone control provides high input 
impedance and low noise characteristics for 
high-fidelity audio applications. — "FET Data- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 6-26-6-36. 




O OUTPUT 



0.0033 uF 



66 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




Rl, R2. R3, R4 • 500K 

FOUR-CHANNEL MIXER— All four sections of 
RCA CA3048 quad differential amplifier are uti- 
lized in linear mixer providing gain of 20 dB for 
each channel. Designed for use with load of 10K 
or larger. All inputs are high impedance. — E. M. 
Noll, "Linear IC Principles, Experiments, and 
Projects," Howard W. Sams, Indianapolis, IN, 
1974, p 173 and 179. 



BOOST BASS CUT 

„„„, c (LINEAR) 

047^1- 240 kfl 5 Mn 240 kfl 
>— )l 



■FOR SINGLE SUPPLY 




±15 dB BASS AND TREBLE BOOST 
AND CUT AT 100 Hz AND 10 kHz, 
RESPECTIVELY 

25 VOLTS p-p OUTPUT AT 20 kHz 
-3 dB AT 70 kHz FROM I kHz 
REFERENCE 
TONE CONTROL NETWORK dB FL4T POSITION GAIN 



51 kfl 5 Mil 51 kS2 

(LINEAR) 

BOOST TREBLE CUT 



FOR DUAL SUPPLIES 



047jiF 




0.1 /iF 



BAXANDALL TONE CONTROL— Utilizes high 
slew rate, high output-voltage capability, and 
high input impedance of CA3140 bipolar MOS 
opamp to provide unity gain at midband along 
with bass and treble boost and cut of ± 15 dB at 
100 and 10,000 Hz. Optional connection for ± 15 
V supply is shown below. — "Circuit Ideas for 
RCA Linear ICs," RCA Solid State Division, So- 
merville, NJ, 1977, p 10. 



EXPAN0OR Siuf 
Ino- 




^>^ 1K 

>- • — \W 
— s — R » 




tri 



-2^1 EXPANDOR 
-)( • — OOUT 




HI-FI EXPANDER— Used in playback of material 
that has been recorded with overload-prevent- 
ing compressor. External opamp is used for 
high slew rate. Adjust distortion trimpot R 9 for 



minimum total harmonic distortion when using 
input of dBm at 10 kHz. Adjust DC shift pot R, 
after this, for minimum envelope bounce with 



tone-burst input. — "Signetics Analog Data 
Manual," Signetics, Sunnyvale, CA, 1977, p 
804-805. 



AUDIO CONTROL CIRCUITS 



67 



INPUT 



-r- 0.47 mF 




OUTPUT 



3W 




*I 



60-dB RANGE FOR AUDIO— JFET acts as volt- 
age-controlled resistor in peak-detecting con- 
trol loop of 741 opamp. Input range is 20 mV to 
20 V, with response time of 1-2 ms and delay 



io kn 



of 0.4 s. Output is about 1 .4 V P-P over entire 60- 
dB range. — N. Heckt, Automatic Gain Control 
Has 60-Oecibel Range, Electronics, March 31, 
1977, p 107. 



AUDIO-OPERATED RELAY— Addition of two 
general-purpose transistors to 555 timer gives 
audio-triggered relay that can be used for au- 
tomatic recording of output of channel-moni- 
toring radio receiver or data from any audio link. 
Adjustable time delay R keeps control circuit 
actuated up to 5 s (determined by R and C) to 
avoid cycling relay during pauses in speech or 
dropouts in data. Q1 is NPN, and Q2 is PNP. At- 
tack time equals very short pull-in time of 5-V 
reed relay K. Adjust 10K input pot just below 
point at which K pulls in when there is no audio 
input. — R. Taggart, Sound Operated Relay, 73 
Magazine, Oct. 1977, p 114-115. 



DIFFERENTIAL-AMPLIFIER CUPPER— Provides 
gain as well as precise symmetrical clipping for 
improving intelligibility of speech fed into radio 
transmitter. Circuit reduces dynamic range of 
energy peaks to bring them closer to average 
energy level. When inserted in series with mi- 
crophone, use of clipper gives at least 6-dB in- 
crease in effective power. Signals are passed up 
to certain amplitude but limited above this 
level. — B. Kirkwood, Principles of Speech Pro- 
cessing, Ham Radio, Feb. 1975, p 28-34. 



MSB 

e — 



DIGITAL 
INPUTS 



O- 
O— 

o— 



AC 

INPUT 

?SV MAX O- 



R1 

5KS! ; 

R2 20KS! | 

-V/v- 



REF 
'+10V 




+15V a 



A1 
DAC-76 



6 

-1SV 



6 

+15V 



FOR 78dB CONTROL RANGE, USE PIN 1 AS LSB 
(AS SHOWN). FOR 72dB CONTROL RANGE. USE 
PIN 9 AS LSB, GROUND PIN 1. 




SQUELCHABLE AMPLIFIER— Circuit designed 
for portable FM scanners and two-way walkie- 
talkie radios can be turned off by noise or by 
control signal to minimize battery drain. When 
squelched, LM388 opamp-transistor-diode 
array draws only 0.8 mA from 7.5-V supply. 
Diodes rectify noise from limiter or discrimina- 
tor of receiver, producing direct current that 
turns on Q, and thereby clamps opamp off. Volt- 
age gain is 20 to 200, depending on value used 
for R,. Power output without squelch is about 
0.5 W for 8-ohm loudspeaker. — "Audio Hand- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 4-37-4-41. 



+ COUT 
— II 



AC 

-O) 



TWO-QUADRANT EXPONENTIAL CONTROL— 
Decibel-weighted control characteristic of Pre- 
cision MonolHhics DAC-76 D/A converter 
matches natural loudness sensitivity of human 
ear, to provide much greater useful dynamic 
range for controlling audio level. Control range 



can be either 72 or 78 dB, depending on pin con- 
nections used. 8-bit word control input can be 
interfaced with standard TTL-compatible mi- 
croprocessor outputs. To avoid annoying out- 
put transients during large or rapid gain 



OP-02 GENERAL PURPOSE 
OP-16 FAST SETTLING 
OP-01 LOWEST DISTORTION 



changes, use clickless attenuator/amplifier (also 
given in application note). — W. Jung and W. 
Ritmanich, "Audio Applications for the DAC-76 
Companding D/A Converter," Precision Mono- 
lithics, Santa Clara, CA, 1977, AN-28, p 2. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CLAMPING WITH OPAMPS— Circuit is used 
after stage of AC amplification to clamp mini- 
mum level of signal voltage to V for signals 
having amplitudes between 10 mV and 10 V. 
With 250-*iF electrolytic for C, sinusoidal wave- 
forms between 3 and 10,000 Hz are clamped 
with little distortion. Overall gain is unity. — C. 
B. Mussell, D.C. Level Clamp, Wireless World, 
Feb. 1975, p 93. 



from j 
Detector 



I 2N3820 ! 



2N3820 Enisting 

■ ii - » | . Audio Amp 




AF COMPRESSOR— Developed for use in com- 
munication receiver where signals vary so 
greatly that even modern AVC systems cannot 
level all signals. Circuit is AVC that sets maxi- 
mum audio level which will not be exceeded. 
Uses one FET as series attenuator controlled by 
DC voltage derived from audio output. R 3 per- 
mits adjustment of compression level. — C. E. 
Richmond, A Receiver Audio Compressor, CO, 
June 1970, p 35 and 86. 



100mv 

(volts RMS) 
o 



4=-V 



1pf 



IM567 



10KS2 



'4.7KS2 




PNP 
. 2N3906 



Relay up to i +5 to + 9». o 

50ma. < m 



CI 



<°-\ 



0.01 



Ql 



Ri VCR7N 

-VA — ' 
l N ^ 10 K and 47 K 



« 



R2 
I — VAN > 

5K 



3V 



VOLTAGE-CONTROLLED ATTENUATOR— 
Used to control low-level audio signals with 
variable DC voltage of ±3 V. Control pot can be 
remotely located. Highest possible output is 
equal to input level, occurring when gate bias 
is set close to pinchoff value. Output is mini- 
mum when gate bias is zero. — E. M. Noll, "FET 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 2nd Ed., 1975, p 258- 
260. 



TONE-DRIVEN RELAY— LM567 tone decoder 
will respond to frequency between 700 and 
1500 Hz, determined by setting of 10K pot. 
When input of 100 mVRMS at preset frequency 
arrives, output of IC goes low and energizes 
relay through transistor. Tone can be obtained 
from audio oscillator or telephone Touch-Tone 
pad. Relay contacts can be used to turn desired 
device on or off. — J. A. Sandler, 9 Easy to Build 
Projects under $9, Modern Electronics, July 
1978, p 53-56. 



"£ 

R 



C13 
•2.2juF 



J< >l 




-I-C1 -L-C3 



lH-*-~r 



2N930 ' 



2.2AIF 
40V 



tLC4 JL-C5 „., 

' "Md 2jaf <iok 




C7 

47«r 
<ov 



me 
I — VW- 

100k 



-vw 



C9 

-2.2j)F 
40V 



EQUALIZER — Designed for use between input 
jack and microphone of amateur transmitter, to 
keep bandpass response between limits of 
about 200 and 3100 Hz. Circuit also provides 
measure of volume compression, improving 
transmitter efficiency. Construction and adjust- 



vW — •-•- A/V^ 1 

33k J 10k | | 



■ OVjF 
10V 



ment details stress importance of eliminating 
ground loops and RF feedback. U1 is voltage- 
controlled amplifier in feedback loop, with 741 
opamp U2 as compression detector.- U2 is 
biased so output is almost at ground, and no 
feedback voltage is applied until input to U2 ex- 



ceeds 0.9 V. U1 thus operates in linear mode at 
maximum gain until output voltage exceeds 0.9 
V, when voltage is applied to U1 and gain of IC 
is reduced.— R. Tauber, The Equalizer, QST, 
March 1977, p 18-20. 



AUDIO CONTROL CIRCUITS 



69 



liSWRMS 



O-J I— v-v 



o— I |~^wv 



o— J I— vw 



o— I kwv 




Output 9 



QUAD GAIN CONTROL — Combination of Na- mum output. Temperature sensitivity of FET 
tional AM97C11 quad FET and LM324 quad can be reduced by using silicon resistor for 
opamp gives tracking gain control having 40-dB opamp feedback resistor HI. — "FET Databook," 



range. Bandwidth is 10 kHz minimum, and S/N 
ratio is better than 70 dB for 4.3-VRMS maxi- 



National Semiconductor, Santa Clara, CA, 1977, 
p 6-39-6-46. 



JT^ 

500KH 
Ao-^f— p-VW 2 " 



BC_^(- 



5O0KS2 



1/uf 



Co-i«- 



-r- WV- 



500KT2 



1 M f 



Do-^(- 



tr~ 



500KH 




2.2KH . 



1 M f 



■i-vyv — ' 



FOUR-CHANNEL MIXER— Combines AF signals 
from one to four sources into single audio signal 
for input of LM381 opamp that serves also as 
preamp. Shield mixer circuit and use shielded 
cable for all input leads to avoid pickup of 60-Hz 
field by high-gain opamp. Increasing supply 
voltage from minimum of 9 V boosts output sig- 
nal voltage. — J. A. Sandler, 9 Easy to Build Proj- 
ects under $9, Modem Electronics, July 1978, 
p 53-56. 




NOISELESS AUDIO SWITCH— Deglitched cur- 
rent-mode switch using JFET can be placed di- 
rectly on printed-circuit board instead of front 
panel, to minimize hum pickup and crosstalk. 
JFET allows transition time of drive to be ad- 
justed with series resistor R and shunt capacitor 
C to provide noiseless switching of AF signals. 
Diode type is not critical. Any number of 
switches can be ganged. — "Audio Handbook," 
National Semiconductor, Santa Clara, CA, 1977, 
p2-62. 



CHAPTER 5 

Audio Measuring Circuits 



Includes S-meters and VU meters, along with circuits for measuring AF 
distortion and flutter, peak program meter tester, and clipping-point indicator. 
See also Frequency Measuring and Frequency Multiplier chapters. 



FLUTTER METER— Signetics 561 N PLL detects 
frequency variations in 3-kHz tone recorded on 
magnetic tape for test purposes. Frequency of 
VCO in 561 N is set to nominal 3 kHz with 5K pot. 
Demodulated output is AC coupled to amplifier 
having high input impedance. Either CRO or 
true RMS voltmeter can be used to make RMS 
flutter readings. To calibrate circuit, feed in 3- 
kHz tone from oscillator and measure output 
level shift when frequency is offset 1%. — "Sig- 
netics Analog Data Manual," Signetics, Sunny- 
vale, CA, 1977, p 860. 



TUNABLE BANO 
PASS FILTER 




TO OSCILLOSCOPE OR 
RMS VOLTMETER 



HARMONIC-DISTORTION METER— Used to 
measure total harmonic distortion of audio am- 
plifier, component, or network. Pure sine-wave 
signal is applied to device under test, and out- 



put of device is fed to AF input of distortion 
meter. After setting S2 to appropriate fre- 
quency range, close SI, set S3 at A, set S4 at 
appropriate voltage range, and adjust R1 for 
full-scale meter deflection. Record this voltage 
as E,. Set S3 to B, tune C3 for null, then set S4 



0-50 DC 
MICROM/IMETER 

to successively lower ranges for accurate read- 
ing of voltage at null. Record residual null volt- 
age as E 2 . Percentage distortion is then 10OEJ 
E,.— R. P. Turner, "FET Circuits," Howard W. 
Sams, Indianapolis, IN, 1977, 2nd Ed., p 147- 
150. 



70 



AUDIO MEASURING CIRCUITS 



71 



replay amp 
output ' 



record amp/v. 
output 



■+13-5V (unswitched) 



IC 



kVR- 





4xOA95 


4 




+ 




^ § 


+ 






c 25 






^p. 







. set zero VU level 
to 2 25V r.m.s 



IC DRIVE FOR VU METER— Used in high-quality 
stereo cassette deck operating from AC line or 
battery. Meter rectifier bridge is in feedback 
loop of opamp, to give highly linear AC/DC con- 
version with flat frequency/amplitude response 
and short voltage rise time at low cost. Article 
gives all other circuits of cassette deck and de- 
scribes operation in detail. — J. L. Linsley Hood, 
Low-Noise, Low-Cost Cassette Deck, Wireless 
World, Parti— May 1976, p»36-40 (Part 2— June 
1976, p 62-66; Part 3— Aug. 1976, p 55-56). 



ADD-ON S-METER— Although designed for use 
with Clegg FM-27B 2-meter FM receiver, circuit 
can be readily adapted to other receivers. Am- 
plifier brings low-level 455-MHz IF signal up to 
level suitable for driving meter. For other IF, 
such as 10.7 or 11.7 MHz, capacitor values 
should be changed accordingly. Any NPN tran- 
sistor with beta of 30 or more at IF value can be 
used. Diodes can be any type. Supply should be 
regulated but can be 7-14 V. Output of diode 
detector will vary from to 1 V at nominal 
impedance of 20K; for best result, meter with 
20- to 50-fiA movement can be used. — M. Stern, 
FM-27B S-Meter, QST, Dec. 1976, p 35. 




JL C "2~ , ZZZ 



J1 PI 



METER ADJ. 
400k 



X^ 



METER 
(SEE TEXT) 





-38V 



CLIPPING-POINT INDICATOR— Uses LED to in- 
dicate when clipping distortion begins in 50-W 
power amplifier. Display circuit is referenced to 
negative supply, making detection level inde- 
pendent of supply variation; circuit thus works 
equally well for instantaneous, music, or con- 
tinuous overloads. Tr, is normally turned hard 
on and Tr 2 is off. When overload makes collec- 
tor-emitter voltage of lower amplifier output 
transistor approach saturation, Tr, begins to 
turn off and C, charges through D, so LED turns 
on. Attack time is chosen to make single 3-ms 
overload transient visible. — J. Dawson and K. 
Northover, L.E.D. Clip Indicator, Wireless 
World, Jan. 1976, p 60. 



-0-38V 



72 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



ADDING S-NIETER— Circuit works well with 
most all-band receivers. Q1 may also be SK- 
3011, NR5, TR-10, or DS75. Q2 may also be HE- 
1, SK-3005, or TR-06. Value of 1.2-megohm 
input resistor may need to be adjusted depend- 
ing on AVC voltage, to prevent strong signals 
from overloading meter. — Novice Q & A, 73 
Magazine, Feb. 1977, p 127. 



CIRCUIT-* 1 




do 




1C8 Q 
CL 



zfOfk 



- SERIAL PCM OUT 




LEDs DISPLAY VU PEAKS— Exponential coding 
of Precision Monolithics DAC-76 D/A converter 
is used to good advantage in peak-reading VU 
indicator with logarithmic weighting, driving 
LED display. Input audio is converted by DAC- 
76, CMP-01 comparator, and 2502 successive- 
approximation A/D converter after being sam- 



pled by sample-and-hold input circuit. A/D con- 
verter is clocked at 500 kHz and completes con- 
version every 18 ps, which is fast enough to 
track audio signals. 4 most significant magni- 
tude bits drive 3205 1-of-8 decoder which is en- 
abled by most significant bit. Resulting eight 
output levels, separated by 3-dB increments. 



drive 8-bit RS latch using 74279 chips, updated 
every 25 ms by 40-Hz display multiplex clock.— 
W. Jung and W. Ritmanich, "Audio Applications 
for the DAC-76 Companding D/A Converter," 
Precision Monolithics, Santa Clara, CA, 1977, 
AN-28, p 6. 



AUDIO MEASURING CIRCUITS 



73 




1-mA S-METER— Amplifier designed for 1-mA 
meter movement consists of two-stage voltage 
amplifier driving meter rectifier. FET input pro- 
vides high impedance to detected audio and 
minimizes loading and distortion problems. Q2 
is common-emitter voltage amplifier with sim- 
ple positive-pulse rectifier for meter. C1 filters 
rectified audio signal. AF input for S-9 reading 
is 25-30 mV P-P and for full scale is 50-60 mV 
P-P. Frequency response is 500 Hz to 10 kHz. — 
M. A. Chapman, Solid-State S-Meters, Ham 
Radio, March 1975, p 20-23. 



*7r* 

35jjF j 
I5V 







^35„F §200 ^r35, 

I" i I" 



5-mA S-METER — Circuit designed for 5-mA 
meter movement uses two-stage voltage am- 
plifier Q1-Q2 with emitter-follower output Q3 
serving as impedance-matching stage. AF input 
for S-9 reading is 25-30 mV P-P and for full scale 
is 50-60 mV P-P. Frequency response is 500 Hz 
to 10 kHz. — M. A. Chapman, Solid-State S-Me- 
ters, Ham Radio, March 1975, p 20-23. 



0.01 



_r->H. 



0.01 

■=■ i o.oi 



X 



0.01 




AUDIO OUTPUT 



INPUT LIMITING VOLTAGE 30O»V 

RECOVERED AUDIO 450mVRMS 

AM REJECTION (30X AMI 40dB 

DISTORTION 03% 



AUDIO-FREQUENCY METER— Covers 0-100 
kHz in four ranges. Meter reading is indepen- 
dent of signal amplitude from 1 .7 VRMS upward 
and independent of waveform over wide range. 
Linear response means only one point need be 
calibrated in each frequency range. Circuit uses 
two overdriven FET amplifier stages in cascade. 
Square-wave output of last stage is rectified by 
XI and X2. Deflection of meter depends only on 
number of pulses per second passing through 
meter so is proportional to pulse frequency. 
Battery drain is 1.4 mA. — R. P. Turner, "FET Cir- 
cuits," Howard W. Sams, Indianapolis, IN, 1977, 
2nd Ed., p 129-131. 



-24V 

regulated*-^ 



LEVEL DETECTOR— Circuit lights green LED K 
signal at output of audio preamp exceeds 1 V 
peak for predetermined period. Red LED comes 
on when tone-control stage at output of 
preamp is on verge of clipping. VU meter driver 
circuit is also provided. Entire circuit must be 
duplicated for other stereo channel. Article de- 
scribes circuit operation in detail and gives all 
associated circuits used in high-performance 
audio preamp. D, is 1N914; red LED is TIL209 or 
equivalent; green LED is TIL211.— D. Self, Ad- 
vanced Preamplifier Design, Wire/ess World, 
Nov. 1976, p 41-46. 



+ 2AV 
regulated L 



+35V 
unregulated 

^*- peak 




74 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Fundamental 

plus 

harmonics 



MILLIVOLTMETER 




MEASURING AF DISTORTION— Passive high- 
pass 1-kHz filter is used with audio millivolt- 
meter to improve accuracy of distortion mea- 
surements for low-impedance sources at 1 kHz. 
Filter removes low-frequency noise from input 
signal and compensates for loss of harmonic 
frequency. Applications include setting bias and 
recording levels of tape recorder. Adjust R, for 
best null, then adjust R 2 and value of C to equal- 
ize responses at harmonics. — J. B. Cole, Passive 
Network to Measure Distortion, Wire/ess 
World, Jan. 1978, p 60. 



AF VOLTMETER— Although not calibrated on 
absolute basis, either 3 dB or 10 dB of attenua- 
tion can be switched in with SI for measuring 
purposes, internal adjustments are made easily 
by tacking 51-ohm resistor temporarily across 
input, then driving input with step attenuator 
fed with audio power at -10 dB by generator 
having 50-ohm pad in its output. CR1-CR4 are 
1N914. — W. Hayward, Defining and Measuring 
Receiver Dynamic Range, QST, July 1975, p 15- 
21 and 43. 



10 

v\AA-0 + 12 v 





+12V 5mA 



PEAK PROGRAM METER TESTER— Used with 
5-kHz audio oscillator to produce tone bursts of 
1.5, 5, 10, and 100 ms, as required for checking 



response of program meter to tone bursts. 
Transistors Tr 3 and Tr 4 form mono with 
switched timing capacitors. Article covers cali- 



bration and use. — E. T. Garthwaite, Tone Burst 
Generator for Testing P.P.Ms, Wireless World, 
Aug. 1976, p 53. 



AUDIO MEASURING CIRCUITS 



75 




AUDIBLE S-METER— When connected to re- 
peater, circuit generates tone burst 3 s after 
input signal has dropped out, with duration of 
60 ms. Pitch of tone varies inversely with signal 
strength; highest pitch of 3500 Hz thus repre- 
sents weak signal, and 350-Hz pitch corre- 
sponds to strongest input signal. Can be used 
to check performance of transmitters and an- 



tennas using that repeater. Repeater receiver 
must have S-meter, as in RCA CA3089E receiver, 
output of which can be fed to terminal A of cir- 
cuit. Switch changes output from S-meter to 
aud ible encoder. Input B goes to squelch, C goes 
to +12 V source that is on when receiver is on. 



and D provides tone output for feed to audio 
amplifier and loudspeaker. Unlabeled transis- 
tors can be any medium-gain small-signal NPN 
and PNP silicon, comparableto European BC107 
and BC177.— F. Johnson, Audible S-Meter for 
Repeaters, Ham Radio, March 1977, p 49-51. 



CHAPTER 6 

Automatic Gain Control Circuits 



Includes circuits providing automatic control of gain for one or more stages in 
AF, RF, IF, video, or balanced modulator sections of receivers. See also 
Amplifier, IF Amplifier, and Receiver chapters. 



AGC WITH MANUAL CONTROL— Used in 1.8-2 
MHz communication receiver having wide dy- 
namic range. R3 serves as manual IF gain con- 
trol. R2 provides gain variation from 6 to 40 dB 
for AGC amplifier. Delay is about 1 s. Input is 
taken from primary of transformer that drives 
product detector of receiver, and AGC output 
goes to CA3028A IF opamp. Two-part article 
gives all other circuits of receiver. — D. DeMaw, 
His Eminence— the Receiver, QST, Part 2 — July 
1976, p 14-17 (Part 1— June 1976, p 27-30). 



AGC AMP 
.1 



-H2V 
AGC 9 



_^w^J S0 F U R L ^ ~ AG - C - 



+9V TO+ZV 




S-METER 
MA )M1 
0-1 



0+12V 



100 pF 




BANDPASS a 250 Hz TO 250 KHz 



AGC WITH CMOS LOGIC— First stage U 2 , using 
CD4007AE, is wired as two-line demultiplexer 
with only one output acting as transmission 
gate. Gain is lower in first stage to reduce noise. 



U, is used as three-stage high-gain audio am- 
plifier in which first two stages have low-pass 
filtering for stability. AGC voltage, developed 
from audio output, is fed back to U 2 to turn 



transmission gate off when gain must be re- 
duced. Audio output is about 2.5 V P-P for inputs 
of 2 mV and greater.— K. H. Fleischer, Turn Dig- 
ital CMOS ICs into a Low-Level AGC Amplifier, 
EDN Magazine, Oct. 5, 1977, p 99. 



76 



AUTOMATIC GAIN CONTROL CIRCUITS 



77 




3.0 k 12 k 



as10 mVrms * 



VAGCO 




MFE2012 



0.1 ILF 



HANG AGC— Provides very fast attack time 
with no AGC pop. Diodes are 1N914. When volt- 
age across R10-C8 decays below that across R9- 
C7, 03 conducts and clamps AGC bus to ground. 
AGC threshold is determined by value of R T , be- 
tween 100K and 470K. AGC line must have high 



impedance, as with FET IF system. With IC or 
bipolar IF amplifier, use low-impedance driver. 
T1 is audio transformer with 10K primary and 
2K secondary (Radio Shack 273-1378).— D. Ste- 
vens, Solid-State Hang AGC, QST, July 1975, p 
44. 



FET GIVES 30-dB GAIN RANGE— Only 1-V 
change in gate-source voltage of FET changes 
voltage gain overfull range. Possible drawback 
is harmonic distortion due to unbypassed emit- 
ter degeneration. — "Low Frequency Applica- 
tions of Field-Effect Transistors," Motorola, 
Phoenix, AZ, 1976, AN-S1 1A, p 8. 



no kn 



+15V 



OUTPUT 

Vo \- 

(0.2 V pk-pk, 65 Hi) 



* *— VW- 

20.5 kn 




(40mV-4.1 V pk-pk, 65 Hz) 



OP AMPS: 741 



-15 V 



0i^ 1N914 





C 2 

vi' 6.8 lit 
"^ (10 V) 



TWO-DECADE RANGE— Output is maintained that determines gain of A,. A 2 and diodes form Gain Control Operates over Two Decades, Elec- 

at 0.2 V for inputs from 40 mV to 4.1 V. Voltage- full-wave rectifier. Developed for use in radar tronics, Aug. 16, 1973, p 99-100; reprinted in 

controlled JFET serves as variable control ele- seeker device to prevent overload of amplifier "Circuits for Electronics Engineers," Electron- 

ment. Comparator A 3 produces error voltage as target gets closer. — C. Marco, Automatic ics, 1977, p 44-46. 



78 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



r-vWA 

0.01 ft 62k 

© |(- 



INPUT 



+ V «| OUT 

+ — • ,/w— , o-oi J 

1k V^H( — © 



OP. IdBm) 



i20k 



0.01 f f 



,. CONTROL 3 - 9 „ k 



Q1 
2N3933 



VOLTAGE 



4.7k 



:.»k ^ c 

v — T ""V 



02 
2N3933 



Q3 
2N3933 



LOW PHASE SHIFT— Voltage-controlled ampli- 
fier has less than 3° phase shift over gain-control 
range of 40 dB at frequencies up to 10 MHz, as 
required for AGC circuits. Current generator 02 
controls gain of wideband resistance-coupled 
amplifier Q1. Gain of Q1 increases linearly with 
amplitude of positive control voltage on base of 
02. — A. H. Hargrove, Simple Circuits Control 
Phase-Shift, BDN Magazine, Jan. 1, 1971, p 39. 



P in (dBm) 



AGC VOLTAGE 




30-MHz AGC LOOP— Low-pass filter serves as 
loop giving closed-loop bandwidth of at least 5 
kHz. Loop operates in square-law region of de- 
tector diode. Inputs to IF amplifier are in range 
from -60 dBm to - 1 dBm, and AGC action pro- 
vides 30-MHz IF output of -15 dBm. Power 



splitter ensures that detector also operates at 
-15 dBm. Article gives design equations and 
performance curves. — R. S. Hughes, Design Au- 
tomatic Gain Control Loops the Easy Way, BDN 
Magazine, Oct. 5, 1978, p 123-128. 




AUDIO AGC USING FET— DC control voltage 
obtained from key signal point in audio ampli- 
fier is applied to gate of FET to vary bias. Gain 
of stage varies inversely with gate bias voltage. 
When control voltage is V, voltage gain of 
stage is 10 and maximum undistorted output 
signal is 1 VRMS. When control voltage is 6 
VDC, output is reduced to 0.5 mVRMS, giving 
better than 90-dB range for AGC control. — R. P. 
Turner, "FET Circuits," Howard W. Sams, Indi- 
anapolis, IN, 1977, 2nd Ed., p 39-40. 



CONTROL-VOLTAGE INPUT 
(0-6 V del 




50-54 MHz RF-AGC AMPLIFIER— Developed for 
6-meter SSB transceiver to give minimum of 15- 
dB power gain, low noise figure, and good sig- 
nal-handling capability when AGC is applied. 



AGC control resembles bipolar cascode circuit 
using differential pair with current source, al- 
though operation does not involve changing 
amplifier bias level. With increasing AGC volt- 



age, Q3 begins to turn on, shunting more and 
more signal current away from 02 and thereby 
decreasing stage gain. Input transformer is 
wound on small toroid core. Range of AGC volt- 
age is 0-1.2 V.— A. Borsa, High-Performance 
RF-AGC Amplifier, Ham Radio, Sept. 1978,p64- 



AUTOMATIC GAIN CONTROL CIRCUITS 



79 



0.1 M F 



0.1 jjF 




0.1 |iF 0.1 flF 

Hh^I )\ 



ioon 




CONTROL WITH EXTERNAL DIODE— External 
resistances normally used with Motorola 
MC1552 video amplifier are replaced by 1N914 
or equivalent diode so gain of amplifier is de- 
termined by AGC current through diode. Ar- 
rangement gives wide range of gain control, but 
lowest obtainable level of gain is normal un- 
modified gain of amplifier. Same circuit can be 
used with MC1553 high-gain video amplifier. — 
"A Wide Band Monolithic Video Amplifier," Mo- 
torola, Phoenix, AZ, 1973, AN-404, p 10. 



CONTROL AT LOW GAIN LEVELS— Diode is 
used as variable impedance in voltage-divider 
network at input of video amplifier to provide 
AGC at lower gain levels than could be handled 
with more conventional external-diode circuits. 
Voltage gain for Motorola MC1552 decreases 
from about 50 for 1-mA AGC control current to 
about 20 for 8 mA. For MC1553 high-gain video 
amplifier, gain drops from 400 at 1 mA to 25 at 
8 mA.— "A Wide Band Monolithic Video Ampli- 
fier," Motorola, Phoenix, AZ, 1973, AN-404, p 11. 



DC AMPLIFIER 



DIFF. 
AMPLIFIER 

+ I2V 



9-MHz 

l-T SIGNAL 

INPUT 




£ 



1 EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS ( JjF ) ; 
OTHERS ARE IN PICOFARADS ( PF OR jijjF)', 
RESISTANCES ARE IN OHMS ; 
k-1000. MMOOO 000. 



AGC LOOP FOR MOSFETs— Used at output of 
9-MHz IF amplifier in commercial receiver to di- 
vide desired control-voltage magnitude and 
swing for FT0601 MOSFETs in IF strip. MOSFETs 
are biased by 2.1-V zeners in source leads In 
FETs, to drive gate-2 voltage sufficiently nega- 
tive for full AGC action. — G. Ricaud, Modifying 
the W1CER/W1FB AGC Loop for Use with MOS- 
FET l-F Amplifiers, QST, June 1977, p 47. 




+ 6 V 



-0-6 V 



WIDEBAND AGC AMPLIFIER— Combination of tude of AC input signal, for varying gain of bal- out attenuation.— "Signetics Analog Data Man- 
592K opamp and MC1496K balanced modulator anced modulator. Unbalancing carrier input of ual,"Signetics,Sunnyvale,CA,1977,p709-710. 
gives DC output signal proportional to ampli- modulator makes signal pass through with- 



80 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Rf 10k 



fin 10 k 




2N4416 •=■ 



AGC AMPLIFIER— FET used in conjunction with 
opamp permits varying of gain by changing 
ratio of R f to R itl . Offset voltage in output due to 
input bias currents is minimized by placing FET 
in parallel with 5.1K resistor between nonin- 
verting leg of opamp and ground, so resistance 
varies with changes of R ln . — "Low Frequency 
Applications of Field-Effect Transistors," Mo- 
torola, Phoenix, AZ, 1976, AN-511A, p 9. 




POSITIVE PEAK DETECTOR— CA3100 bipolar 
MOS opamp is connected as wideband nonin- 
verting amplifier to provide essentially constant 
gain for wide range of input frequencies. Diode 



clips negative half-cycles, so output of transis- 
tor is proportional only to positive input 
peaks. — "Circuit Ideas for RCA Linear ICs," RCA 
Solid State Division, Somerville, NJ, 1977, p 16. 




AGC WITH FET — FET serves as nonlinear ele- input signal so FET input is less than 25 mV for voltage of FET. — R. D. Pogge, Designers' Guide 
ment in fast-acting instrumentation circuit han- inputs up to 2 VRMS. Article covers design and to: Basic AGC Amplifier Design, EDN Magazine. 
dling wide range of signals. R, and R 2 attenuate performance. Gain is almost linear with gate Jan. 20, 1974, p 72-76. 



CHAPTER 7 

Automotive Circuits 



Includes capacitor-discharge, optoelectronic, and other types of electronic 
ignition, tachometers, dwell meters, idiot-light buzzer, audible turn signals, 
headlight reminders, mileage computer, cold-weather starting aids, wiper 
controls, oil-pressure and oil-level gages, solid-state regulators for alternators, 
overspeed warnings, battery-voltage monitor, and trailer-light interface. For 
auto theft devices, see Burglar Alarm chapter. 



SOLID-STATE AUTO REGULATOR— Replaces 
and outperforms electromechanical charging- 
voltage regulator in autos using alternator sys- 
tems. Prolongs battery life by preventing un- 
dercharging or overcharging of 12-V lead-acid 
battery. Uses LM723 connected as switching 
regulator for controlling alternator field current. 
R2 is adjusted to maintain 13.8-V fully charged 
voltage for standard auto battery. Article gives 
construction details and tells how to use exter- 
nal relay to maintain alternator charge-indica- 
torfunction in cars having idiot light rather than 
charge-discharge ammeter. Q1 is 2N2063A 
(SK3009) 10-A PNP transistor.— W. J. Prud- 
homme. Build Your Own Car Regulator, 73 
Magazine, March 1977, p 160-162. 



TO 


IGNITION 
ITCH 










Ql 

2N2063A 




FIELD 


I38V 


01 
r-!8V 
L IW ; 

ZENER 


Rl 
470fl 

R2 




12 




i 










It 


5in 






4 


v*- 

ICI vc 
LM723 

INV. VOUT 

VREF 

VZ 

N.I. 

V" 




1 






-02 




■ soon 

R3 
470ft 


6 




k IN4007 














9 








5 










7 












rt 


7 GND 







I ALTERNATOR 

FIELD 
I WINDING 



CD4001 



SPEED 

«,— 

(MPH) 



?? ?? 



53 2 2 2' 2® 

CD4527 

CLK OUT 



l-HCASC 

E.„ ST C S 



P^ 



R,(+) 



FLOW 



IGAL/HR) 



f ??f 



2 3 2 2 2 1 2° 

CD4527 

CLK OUT 

iHCASC 

E,_ ST C S 



3-t 




r 



U/D 



CD4510 

CLK 

Q, Q 2 Q 3 Q « 



CLK 2» 

CD4S27 2 i 

2» 



OUT 



•V: 



U/D 

c.„ c. 



CD4510 

CLK 

Q, Q 2 Q 3 Q 4 



MOST SIGNIFICANT BITS 



R,(-) 



CLK 2° 

CD4527 ,, 
CASC 

E 2 1 

ST OUT 2 ' 



J 



^t: 



LEAST SIGNIFICANT BITS 



CD4511 



7-SEGMENT 
LED DISPLAYS 



B - B 



MILEAGE COMPUTER — Fuel consumption in 
miles per gallon is continuously updated on 2- 
digit LED display. Entire system using CMOS ICs 
can be built for less than $25 including gas-flow 
sensor and speed sensor, sources for which are 
given in article along with operational details. 



Circuit uses rate multiplier to produce output 
pulse train whose frequency is proportional to 
product of the two inputs. Output rate is time- 
averaged. Speed sensor, mounted in series with 
speedometer cable, feeds speed data to CD4527 
rate multiplier as clock input. Gas-flow sensor. 



mounted in series with fuel line, feeds clock 
input of other rate multiplier. — G. J. Summers, 
Miles/Gallon Measurement Made Easy with 
CMOS Rate Multipliers, EDN Magazine, Jan. 20, 
1976, p 61-63. 



81 



82 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



PARAMETRICS 
400075 SCHOTTKY 
DIODE OR EOUIV 




IfF 



^I5V 



lOO^F 

15V '' 



♦ 12V 



AUDIO AMP 
MODULE 




8 OHM 
SPEAKER 



w 



10.5-GHz RADAR DETECTOR— Picks up CW 
Doppler traffic radar signals in X-band region at 
10.525 GHz and alerts speeding driver with 
audio tone. Article also tells how traffic radars 
work. By adding 10.5-GHz oscillator, same cir- 
cuit can be used in 10.5-GHz amateur radio band 
for communicating with other cars using this 
band. Dimensioned diagram of horn is given. — 
S. M. Olberg, Mobile Smokey Detector, 73 Mag- 
azine, Holiday issue 1976, p 32-35. 



SPEED TRAP — Time required for auto to acti- 
vate sensors placed measured distance apart on 
driveway or road is used to energize relay or 
alarm circuit when auto exceeds predetermined 
speed. If speed limit chosen is 15 mph, set de- 
tectors 22 feet apart for travel time of 1 s. Sen- 
sors can be photocells or air-actuated sole- 
noids. For most applications, R1 can be 
1-megohm pot. Transistor type is not critical. 
Values of R2 and C2 determine how long alarm 
sounds. — J. Sandler, 9 Projects under $9, Mod- 
ern Electronics, Sept. 1978, p 35-39. 



4.7 Kfi 
-WV— i 




1N4147 



TSy- 



-WAr- 1 



1 Relay 



4.7 K« 

-wv- 




+ 3 



*> Repeat of above circuit for additional timing 
I s* sequences such as "FAST" and "EXTRA FAST" 

I fit 

L ~M-- 



E 



n>Tr<n 



1 2 3 4 S 6 



t 




-0-^w- 



'■hshhD ^ 



-©- 




DASHBOARD 
PANEL 
LIGHT 
DIMMER 



TO CAR RADIO- 

CAR 

RADIO, 
SPEAKER! 
DASHBOARD 
PANEL LIGHTS 




HEADLIGHT REMINDER— Uses basic oscillator 
consisting of Q2 and Q3 arranged as collector- 
coupled astable MVBR. Power is taken from col- 
lector of Q1 which acts as switch for Q2 and Q3. 
With SI closed and S2 open, oscillator operates. 
Closing S2 saturates 0.1 and stops oscillator. 
Whan used as headlight reminder for negative- 



ground car, B1 is omitted and power for oscil- 
lator is taken from dashboard panel lights since 
they come on simultaneously with either park- 
ing lights or headlights. If ignition key is turned 
on, Q1 saturates and disables Q2-Q3. With ig- 
nition off but lights on, Q1 is cut off and oscil- 
lator receives power. Audio output may be con- 



nected directly to high side of voice coil of car 
radio loudspeaker without affecting operation 
of radio. Almost any NPN transistors can be 
used. Changing values of R4 and R5 changes fre- 
quency of reminder tone. — H. F. Batie, Versatile 
Audio Oscillator, Ham Radio, Jan. 1976, p 72- 
74. 



AUTOMOTIVE CIRCUITS 



83 




HEADLIGHT SWITCH 
IGNITION SWITCH 



+ 36VO 



240 



12 VDC FROM 

IGNITION 

SWITCH 

HEADLIGHTS-ON ALARM— Designed for cars in 
which headlight switch is nongrounding type, 
providing 12 V when closed. When both light 
and ignition switches are closed, transistor is 
saturated and there is no voltage drop across it 
to drive buzzer. If ignition switch is open while 



12 VDC 
BUZZER 



3E100>F 



lights are on, transistor bias is removed so tran- 
sistor is effectively open and full 12 V is applied 
to buzzer through 240-ohm resistor until lights 
are turned off.— R. E. Hartzell, Jr., Detector 
Warns You When Headlights Are Left On, EDN 
Magazine, Nov. 20, 1975, p 160. 



Tl CORE FERROXCUBE 
K3O050I3E 



SN74I0N 
(2) 



+ 12 FROM IGNITION SWITCH 

>- 



IG. COIL >YVv J ' 




+ 5.0 

14 +5.0 



V_JI • a v^, Wv— 

JJ. 910? ^.001 

^-trt •— °— =-lf : 



A 




68 > 



T~l 



21 




m 



ELECTRIC-VEHICLE CONTROL— SCR1 is used in 
combination with Jones chopper to provide 
smooth acceleration of golf cart or other electric 
vehicle operating from 36-V on-board storage 
battery. Normal running current of 2-hp 36-V 
series-wound DC motor is 60 A, with up to 300 
A required for starting vehicle up hill. Chopper 
and its control maintain high average motor 
current while limiting peak current by increas- 
ing chopping frequency from normal 125 Hz to 
as high as 500 Hz when high torque is re- 
quired.— T. Malarkey, You Need Precision SCR 
Chopper Control. New Motorola Semiconduc- 
tors for Industry, Motorola, Phoenix, AZ, Vol. 2, 
No. 1, 1975. 



CD IGNITION— Uses master oscillator— power 
amplifier type of DC/DC converter in which two 
sections of triple 3-input NAND gate serve as 10- 
kHz square-wave MVBR feeding class B PNP/ 
NPN power amplifier through two-gate driver. 
Remaining two gates are used as logic invert- 
ers. Secondary of T1 has 15.24 meters of No. 26 
in six bank windings, with 20 turns No. 14 added 
and center-tapped for primary. T2 is unshielded 
iron-core RF choke, 30-100 /tH, with several 
turns wound over ft for secondary. When main 
20-A SCR fires, T2 develops oscillation burst for 
firing sensitive gate-latching SCR. Storage ca- 
pacitor energy is then dumped into ignition coil 
primary through power SCR. — K. W. Robbins, 
CD Ignition System, 73 Magazine, May 1974, p 
17 and 19. 



points 10k 




ground 



i • S * > 



200 u. 



i **+i tach * 



dwell 'took 



+battery 



R 3 



wD7, 



• +5V 



200 u. 



TACH/DWELL METER— Built around SN7402 
NOR-gate IC. Requires no internal battery; re- 
quired 5 V is obtained by using 50 ohms for R 3 
in zener circuit shown if car battery is 6 V, and 
300 ohms if 12 V. Article gives calibration pro- 



cedure for engines having 4, 6, and 8 cylinders; 
select maximum rpm to be indicated, multiply 
by number of cylinders, then divide by 120 to 
get frequency in Hz. — N. Parron, Tach-Dwell 
Meter, Wireless World, Sept. 1975, p 413. 



84 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+12VO 

ignition 
supply 




.To ignition switch 
"ON" contact 



-12V O 
ignition 
supply 





2N3904 



Optional 

relay 
1 

1 l 

•* 3 

1 r 
L T J 



3 3KS2 B /7^\ "> 

/ To light switch a'f^ 



"ON" contact 

HEADUGHT REMINDER— Photocell energizes 
circuit at twilight to remind motorist that lights 
should be turned on. Indicator can be LED con- 
nected as shown or relay turning on buzzer for 
more positive signal. Circuit can be made au- 
tomatic by connecting relay contacts in parallel 
with light switch, provided delay circuit is 
added to prevent oncoming headlights from 
killing circuit. Mount photocell in location 
where it is unaffected by other lights inside or 
outside car. — J. Sandler, 9 Projects under $9, 
Modern Electronics, Sept. 1978, p 35-39. 



TRANSISTORIZED BREAKER POINTS— Uses 
Texas Instruments BUY23/23A high-voltage 
transistors that can easily withstand voltages 
up to about 300 V existing across breaker points 
of distributor in modern car. Circuit serves as 
electronic switch that isolates points from 
heavy interrupt current and high-voltage back- 
swing of ignition coil, thereby almost com- 



pletely eliminating wear on points. Values are: 
Tr 2 2N3789; Tr 3 (for positive ground version) 
2N3056; 0,-04 1N4001; D 5 18-V 400-mW zener; 
R, 56 ohms; R 2 1.2 ohms; R 3 10 ohms; C600VDC 
same size as points capacitor. Article covers in- 
stallation procedure. — G. F. Nudd, Transistor- 
Aided Ignition, Wireless World, April 1975, p 
191. 



TO BATTERY AND 
ALTERNATOR OUTPUT 
VIA FIELD RELAY AND 
IGNITION SWITCH 




TOCOIL TERMINAL - 
ON STARTER RELAY -*- 
FROM IGNITION SWITCH 



POWER 
DARLINGTON 
MOTOROLA 
MJE1090 



VOLTAGE REGULATOR— Timer and power 
Darlington form simple automobile voltage reg- 
ulator. When battery voltage drops below 14.4 



V, timer is turned on and Darlington pair con- 
ducts. Separate adjustments are provided for 
preset turn-on and turnoff voltages. — "Signet- 



ics Analog Data Manual,' 
CA, 1977, p 731. 



Signetics, Sunnyvale, 



AUTOMOTIVE CIRCUITS 



85 




+12v. from car 




lOKfi 



BATTERY MONITOR— Basic circuit energizes 
LED when battery voltage drops to level set by 
10K pot. Any number of additional circuits can 
be added, for reading battery voltage in 1-V 
steps or even steps as small as 0.1 V. Circuit sup- 
plements idiot light that replaces ammeter in 
most modern cars. LED type is not critical. — J. 
Sandler, 9 Projects under $9, Modern Electron- 
ics, Sept. 1978, p 35-39. 



COLD-WEATHER IGNITION— MuKispark elec- 
tronic ignition improves cold-weather starting 
ability of engines in arctic environment by pro- 
viding more than one spark per combustion 
cycle. Circuit uses UJT triangle- wave generator 
Q1, emitter-follower isolator 02, wave-shaping 
Schmitt trigger Q3-Q4, three stages of square- 
wave amplification Q5-Q7, and output switch- 



ing circuit Q8, all operating from 12-V negative- 
ground supply. 6.2-V zener provides regulated 
voltage for UJT and Schmitt trigger. Initial 20,- 
000- to 40,000-V ignition spark produced by 
opening of breaker points is followed by contin- 
uous series of sparks at rate of about 200 per 
second as long as points stay open. — D. E. 
Stinchcomb, Multi-Spark Electronic Ignition for 
Engine Starting in Arctic Environment, Pro- 
ceadings of the IEEE 7975 Region Six Confer- 
ence, May 1975, p 224-225. 



CL0SE0IN 
TOP GEAR 



0.02„F 




INPUT FILTERS AMPLIFIER 



HIGH-SPEED WARNING— Audible alarm tone 
generator drives warning loudspeaker to sup- 
plement 2-digit speed display that can be set to 
trip when vehicle speed exceeds 55-mph legal 
limit. Engine speed signal is taken from primary 
of spark coil. Switch in transmission activates 
circuit only when car is in high gear. All func- 



tions are performed by sections of LM2900 quad 
Norton opamp. A1 amplifies and regulates 
spark-coil signal. A2 converts signal frequency 
to voltage proportional to engine speed. A3 
compares speed voltage with reference voltage 
and turns on output transistor at set speed. A4 
generates audible tone. Circuit components 



must be adjusted for number of cylinders, gear 
and axle ratios, tire size, etc. 10-/»F capacitor 
connected to A3 can be increased to prevent 
triggering of alarm when increasing speed mo- 
mentarily while passing another car. — "Linear 
Applications, Vol. 2," National Semiconductor, 
Santa Clara, CA. 1976, LB-33. 



86 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



12V LINE 




BUZZER FOR IDIOT LIGHT— Provides audible 
supplement to engine-monitoring indicator 
lamps that are often difficult to see in daylight. 
Uses 2N5434 JFET to provide delay of about 7 
s each time ignition switch is turned on, to allow 
for peaceful starting of car and normal buildup 
of oil pressure when lamp is monitoring oil- 
pressure and engine-temperature sensors. En- 
tire circuit can be mounted inside plastic hous- 
ing of unused or disconnected dashboard 
warning buzzer in late-model car. — P. Clower, 
Audio Assist Gives "Idiot Lights" the "Buzz," 
EDN Magazine, June 20, 1976, p 126. 



OIL-PRESSURE DISPLAY— Red, yellow, and 
green LEDs give positive indication of oil pres- 
sure level on electronic gage console developed 
for motorcycle. Transducer converts oil pres- 
sure to variable resistance R T which in turn var- 
ies bias on transistors. LEDs have different for- 
ward voltages- at which they light, so proper 
selection of bias resistors ensures that only one 
LED is on at a time to give desired indication of 
oil pressure.— J. D. Wiley, Instrument Console 
Features Digital Displays and Built-in Combo 
Lock, EDN Magazine, Aug. 5, 1975, p 38-43. 



+12V|IGNI 




22/35V 
TANTALUM 



WIPER LOW 
SPEED LINE 
t 



^ 






TAB SCR 
POLYPAKS 
92CUI730 
OR SIMILAR 



SN487I 

UNIJUNCTION 

TRANSISTOR 



WIPER CONTROL— Operates wipers automati- 
cally at intervals, as required for very light rain 
or mist. Changing 560K resistor to 500K pot in 
series with 100K fixed resistor gives variable 
control of interval. — Circuits, 73 Magazine, July 
1977, p 34. 



DIODES -I AMP PLASTIC 
RESISTORS- 1/2 WATT 



12 VO- 



" ignition 
!coil 



D 3 

9 V 
1N960 



C 3 
■10.. F 



Rl Ci 

IK 01 F 

->vV* • — )\— 



DISTRIBUTOR 
POINTS 



5K 



*-•> 



. 50K 



555 



^0 1 F 



c 4 _L 

1 F'T* 



200K 
CALIBRATOR 




DISTRIBUTOR-POINT TACHOMETER— 555 
timer receives its input pulses from distributor 
points of car. When timer output (pin 3) is high, 
meter receives calibrated current through R e . 



When IC times out, meter current stops for re- 
mainder of duty cycle. Integration of variable 
duty cycle by meter movement serves to pro- 



vide visible indication of engine speed. — "Sig- 
netics Analog Data Manual," Signetics, Sunny- 
vale, CA, 1977, p 724-725. 



AUTOMOTIVE CIRCUITS 



87 



FRONT OR REAR LH 
TURN SIGNAL LAMP 



FRONT OR REAR RH 
TURN SIGNAL LAMP 




TO STEERING COLUMN 
TURN SIGNAL SWITCH 



AUDIBLE TURN SIGNAL— Gives 3500-Hz audi- 
ble tone each time turn-signal light flashes on, 
to warn driver that signal has not been turned 
off when making less than right-angle turns. 
Schematic shown is for 12-V negative-ground 
systems. For 6-V negative-ground systems, cut 
values of R1 and R2 about in half. For positive- 
ground systems, reverse connections to diodes 
and Sonalert. R1 and R2 are 2.7K 0.5 W. D1 and 
D2 can be any general-purpose small-current 
silicon diode. SA is Mallory SCI .5 Sonalert. — A. 
Goodwin, Turn Signal Reminder, 73 Magazine, 
Holiday issue 1976, p 166. 



1/8 Dl A 

PLEXIGLASS 

ROD 




40.fl 
,, .TRANSISTOR 
"\JRADI0 
N SPEAKER 



LS400 



OIL-LEVEL GAGE — Permits checking crankcase 
oil level from driver's seat. Sensor consists of 
light-conducting Plexiglas rod attached to dip- 
stick, with lamp L, at top of rod and phototran- 
sistor Q, mounted at add-oil mark on dipstick, 
about *k inch below bottom of rod. At normal oil 
level, oil attenuates light between Q, and bot- 
tom end of rod, making phototransistor resis- 
tance high. Pushing test switch makes C, 
charge and saturate O* long enough to activate 
UJT AF oscillator Q 3 and give short tone veri- 
fying that lamp is not burned out and gage is 
working. When oil is low, enough light reaches 
Q 1 to keep Qj saturated after C, charges, giving 
continuous tone as long as switch is pushed. — 
L. Svelund, Electronic Dipstick, EBE Magazine, 
Nov. 1970, p 101. 




W7- 



OPTOELECTRONIC IGNITION— Combination of 
low-cost point-source LED and high-sensitivity 
phototransistor forms optical sensor for posi- 
tion of cam in distributor. Technique eliminates 



problems created by timing drift and distribu- 
tor-shaft play. Sensor head is small enough to 
fit most distributors. Article gives dimensioned 
drawings for shutter design and sensor mount- 
ing, and describes operation of associated ca- 



FPT120 

pacitor-discharge electronic ignition circuit in 
detail. Leads to sensor do not require shield- 
ing. — H. Maidment, Optical Sensor Ignition 
System, Wireless World, Nov. 1975, p 533-537. 



88 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



LOOP 
TANT. filter 

1 MF 100K 

-p W*— 



_n_n_ 




r*? 



a 



TX^ 



3300 pf 



_TL 



I 



n SELECT 
(TABLE 7-31 



OUTPUT FREQUENCY TO 
BE COUNTED FOR 0.5 SEC 



1 



-5- n COUNTER 



_n_n_ 



CONDITIONED 
INPUT 



o W»— 

1.5K 
INPUT FROM 
POINTS OR PICKOFF 



15K 




DIGITAL TACHOMETER— Pulses from auto en- 
gine points or other pickoff are filtered before 
feed to 3130 CMOS opamp used as comparator 
to complete conditioning of input. Pulses are 
then fed through 4046 PLL to divide-by-N 
counter that is set for number of cylinders in 
engine (60 for four cylinders, 45 for six, and 30 
for eight). Output frequency is then counted for 
0.5 s to get engine or shaft speed in rpm. — D. 
Lancaster, "CMOS Cookbook," Howard W. 
Sams, Indianapolis, IN, 1977, p 366-367. 



REGULATOR FOR ALTERNATOR— Simple and 
effective solid-state replacement for auto volt- 
age regulator can be used with alternator in al- 
most any negative-ground system. Circuit acts 
as switch supplying either full or no voltage to 
field winding of alternator. When battery is 
below 13 V, zener D1 does not conduct, Q1 is 
off, 02 is on, and full battery voltage is applied 
to alternator field so it puts out full voltage to 
battery for charging . When battery reaches 1 3.6 
V, Q1 turns on, 02 turns off, alternator output 
is reduced to zero, and battery gets no charging 



AUTOMOBILE 
BATTERY 



■an 



'1 



,R2 

: i2on 



R3 

ion 



<g% 



5296 OR EQUIVALENT 



current. Circuit can also be used with wind-dri- 
ven alternator systems. — P. S. Smith, $22 for a 



Regulator? Never!, 73 Magazine, Holiday issue 
1976, p 103. 



BRAKE 
COMMAND 12 V 



RIGHT-TURN 
COMMAND 




RUNNING-LIGHT 
COMMAND 



K,,K,: 12-Vdc,50-ma RELAY 

250-12 COIL, 3-A CONTACTS 
(ARCHER 275-206 OR SIMILAR) 



TRAILER 

BRAKE-TURN LIGHT 

(LEFT) 



TRAILER 

BRAKE-TURN LIGHT 

(RIGHT) 



TRAILER 

RUNNING 

LIGHTS 



AUTO-TRAILER INTERFACE FOR LIGHTS— 
Low-cost transistors and two relays combine 
brake-light and turn-indicator signals on com- 
mon bus to ensure that trailer lights respond to 
both commands. C, and C2 charge to peak am- 



plitude of turn signal, which flashes about 2 
times per second. Values are selected to hold 
relay closed between flash intervals; if capaci- 
tance is too large, brake signal cannot imme- 
diately activate trailer lights after turn signal is 



canceled. Developed for new cars in which sep- 
arate turn and brake signals are required for 
safety. — M. E. Gihnore and C. W. Snipes, Dar- 
lington-Switched Relays Link Car and Trailer 
Signal Lights, Electronics, Aug. 18, 1977, p 1 16. 



AUTOMOTIVE CIRCUITS 



89 



1-0^ ST, 
• ON 



START 



HIGH 
VOLTAGE 



— STARTER 



STORAGE 
BATTERY 

12V 



+ 12v| 



ARTIFICIAL 
STORAGE BAT 
200V SPARK GENERATOR IGNITI0N 

COIL 



DC TO DC 
CONVERTER 



-nr\ 



iooomfTc, II ? -. 

I POINTS-" 



SCR 



C, =UPTO 1000nF 




CAPACITOR SERVES AS IGNITION BATTERY— 
Developed for use with capacitor-discharge ig- 
nition systems to provide independent voltage 
source for ignition when starting car in very cold 
weather. Before attempting to start car, S, is set 
to ON position for energizing DC-to-OC con- 
verter for charging C, with DC voltage between 
200 and 400 V. Starter is now engaged. If volt- 
age of storage battery drops as starter slowly 
turns engine over, C, still represents equivalent 
of fully charged 12-V storage battery that is ca- 
pable of driving ignition system for almost a 
minute. — W. Stalzer, Capacitor Provides Artifi- 
cial Battery for Ignition Systems, EDN Maga- 
zine, Nov. 15, 1972, p 48. 



WIPER FUSE 
INFUSE BLOCK 




WIPER-DELAY CONTROL— 555 timer provides 
selectable delay time between sweeps of wiper 
blades driven by motor in negative-ground sys- 
tem. Article also gives circuit modification for 



positive-ground autos. Delay time can be varied 
between and 22 s. Timer uses feedback signal 
from cam-operated switch of motor to synchro- 
nize delay time with position of wiper blades. — 



J. Okolowicz, Synchronous Timing Loop Con- 
trols Windshield Wiper Delay, Electronics, Nov. 
24, 1977, p 115 and 117. 



Contact 
breaker 



/ 



R 3 270 
-^VW— 



; 150 

, 3W 



R 4 150 

47 ohT y 



*1tc5 <10k 



D 2 

IN 4001 

-M- 



n. 



R 2 
1k2 



<> 



. R 5 

* ikS 




: : 8 C 2on ■ ~(HG BC,r ° e : : c A : : c. 



Ignition 
inhibit 



-O— o 



-»■ SCR gate 



C 6 

100n 



"12 K T3> 

18k Ik 



^L 



Tacho output 



r 




SCR cathode (/J 10mA 



RPM-LIMIT ALARM— Used with capacitor-dis- 
charge ignition system to provide tachometer 
output along with engine speed control signal. 
When breaker contacts open, d charges and 
turns Tr, on, triggering 555 timer used in mono 



MVBR mode. Resulting positive pulse from 555 
fires control SCR through D e and C 6 . When con- 
tacts dose, D 2 isolates C 1 to reduce effect of con- 
tact bounce. With values shown, for speed limit 
between 8000 and 9000 rpm, use 0.068 /»F for C, 



with four-cylinder engine, 0.047 fiF for six cyl- 
inders, and 0.033 /iF for eight cylinders. LED 
across breaker contacts can be used for setting 
static timing.— K. Wevill, Trigger Circuit for 
C.D.I. Systems. Wireless World. Jan. 1978, p 58. 



90 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



0.1 uF 



1 

2 7 
M, 

(655) „ 

3 6 

4 5 



■-0. 

S15k 

H. 



«-£ 



= 3 - 

0.01 v F 




J T 3 

<2.2k _ 4 



220 

1W 




6.47 uF 



M , 7 Y 0k fi /r yNt ' 



c <, "±- 



0.01 kF 



0.01 mF 



R « 
■VW- 



r)h- 



ALL RESISTORS V,W UNLESS SPECIFIED 
•C,-G.E.TYPE28F5120FC 



T,-6.3V C.T 3A USED AS PRIMARY 
1 17V USED AS SECONDARY 





HV 
OUTPUT 



IGNITION COIL 



TO IGNITION 
SWITCH 



TO EXISTING 



LOW-EMISSION CD— Solid-state capacitor-dis- 
charge ignition system improves combustion 
efficiency by increasing spark duration. For 8- 
cylinder engine, normal CD system range of 180 
to 300 its is increased to 600 /xs below 4000 rpm . 
Oscillation discharge across ignition coil pri- 
mary lasts for two cycles here, but above 4000 



rpm the discharge lasts for one cycle or 300 fis 
because at higher speeds the power cycle has 
shorter times. Circuit uses 555 timer M, as 2-kHz 
oscillator, with Q,-Q 3 providing drive to Q 4 -Q 5 
and T, for converting battery voltage to about 
400 VDC at output of bridge rectifier. When dis- 
tributor points open, Q 7 turns on and triggers 



M 2 connected as mono that provides gate drive 
pulses for SCR. Article describes operation of 
circuit in detail and gives waveforms at points 
a-i. — C. C. Lo, CD Ignition System Produces Low 
Engine Emissions, EDN Magazine, May 20, 
1976, p 94, 96, and 98. 



AUTOMOTIVE CIRCUITS 



91 



TO 

BREAKER 

POINTS 

o 



-Jf — »W — ► 

560 pF 




1N4002 



F/V 
A-8402 



y~ 



I— vW— • 1 



ANALOG 
METER 



+._t 

| OFF 



: 



TACHOMETER— Intech/Function Modules A- 
8402 operating in frequency-to-voltage con- 
verter mode serves as automotive tachometer 
having inherent linearity and ease of calibra- 
tion. Converter operates asynchronously, 
which does not affect accuracy when driving 
analog meter.— P. Pinter and D. Timm, Voltage- 
to-Frequency Converters— IC Versions Perform 
Accurate Data Conversion (and Much More) at 
Low Cost, EDN Magazine, Sept. 5, 1977, p 153- 
157. 



>A 



U ].~ DASH 
*"* SWITCH 




,^-sPt NOMINA 
f °\ SWITCH ! 1 1 



_ i \ annul i 

Q (BOTTOM) ' * 



U* 



$>- 



\ 



L$j 



TIMER FOR WIPER— Provides automatic one- 
shot swipes at preselected intervals from 2 to 
30 s for handling mist, drizzle, or splash from 
wet road. Circuit shorts out homing switch in- 
side windshield-wiper motor, which is usually 



^B SIMPLIFIED 

WIPM CIRCUIT 



CI — 50ufd @ 
25v electroly- 
tic capacitor 

C2— lufd @25v 
electrolytic ca- 
pacitor 

Rl— 50.000- 
ohm potenti- 
ometer 

R2— 33,000- 
ohm resistor 

R3 — 100-ohm 
resistor 

R4 — 47-ohm re- 
sistor 

D — diode 
(Moto. HEP 
135) 

Q— 2N1671B 
unijunction 
transistor 

SCR— SCR 
(Inter. Rect. 
SCR-03) 

S — SPST minia- 
ture toggle 
switch 



in parallel with slow-speed contacts of wiper 
dashboard switch. With wiper switch off and ig- 
nition on, short two switch terminals at a time 
to find pins that start wiper. When blades begin 
moving, remove jumper; blades should then 



finish sweep and shut off. It is these terminals 
of switch that are connected to points A and B 
of control circuit.— V. Mele, Mist Switch— If s 
for Your Windshield Wipers, Popular Science, 
Aug. 1973, p 110. 



CHAPTER 8 

Battery-Charging Circuits 



Includes constant-voltage, constant-current, and trickle chargers operating 
from AC line, solar cells, or auto battery. Some circuits have automatic 
charge-rate control, automatic start-up, automatic shut off, and low-charge 
indicator. 




output 1 



out put 2 



9.6 V AT 20 mA— Developed to charge 200-mAh 
nickel-cadmium batteries for two transceivers 
simultaneously. Batteries will be fully charged 
in 14 hours, using correct 20-mA charging rate. 
Zener diode ensures that voltage cannot exceed 
safe value if battery is accidentally discon- 
nected while under charge. Diode types are not 
critical.— D. A. Tong, A Pocket V.H.F. Trans- 
ceiver, Wireless World, Aug. 1974, p 293-298. 



TRIAD 
F2IA 



I7VAC 
LINE 





I— = 1 

L-K6.3VAC 


> 

600V 




TRIAD 
F2IA 






^\ 




V*6 3\ 


/AC 


\ 



BR I 
(ON HEAT SINK 



TRIAD 
F40X 





ADJUSTABLE FINISH-CHARGE— Uses National 
LM319D dual comparator U2 to sense end-of- 
charge battery voltage and provide protection 
against shorted or reversed charger leads. Final 



charging voltage for 12-V storage batteries is 
adjustable with 2K trimpot. Separate ±15 V 
supply using Raytheon RC4195NB regulator U1 
is provided for U2. D1-D5 are 1N4002 or HEP- 
R0051. D6 is 2N682 or HEP-R1471. BR1 is Mo- 
torola MDA980-2 or HEP-R0876 12-A bridge. 



BR2 is Vara VE27 1-A bridge. Q1 is 2N3641 or 
HEP-S0015.— H. Olson, Battery Chargers Ex- 
posed, 73 Magazine, Nov. 1976, p 98-100 and 
102-104. 



92 



BATTERY-CHARGING CIRCUITS 



93 



10V 



NICKEL-CADMIUM CELL CHARGER— Charges 
four size D cells in series at constant current, 
with automatic voltage limiting. BC301 transis- 
tor acts as current source, with base voltage 
stabilized at about 3 V by two LEDs that also 
serve to indicate charge condition. Other tran- 
sistor provides voltage limiting when voltage 
across cells approaches that of 1K branch of 
voltage divider. Values shown give 260-mA 
charge initially, dropping to 200 mA when V„ 
reaches 5 V and decreasing a Imost to when V c 
reaches 6.5 V.— N. H. Sabah, Battery Charger, 
Wireless World, Nov. 1975, p 520. 





12-V FOR NICADS— Produces constant current 
with simple transistor circuit, adjustable to 15 
or 50 mA with switch and R1. Zener limits volt- 
age at end of charge. Developed for charging 10- 
cell pack having nominal 12.5 V, as used in many 
transceivers.— H. Olson, Battery Chargers Ex- 
posed, 73 Magazine, Nov. 1976, p 98-100 and 
102-104. 



CHARGING SILVER-ZINC CELLS— Used for ini- 
tial charging and subsequent rechargings of 
sealed dry-charged lightweight cells developed 
for use in missiles, torpedoes, and space appli- 
cations. Article covers procedure for filling cell 
with potassium hydroxide electrolyte before 
placing in use (cells are dry-charged at factory 
and have shelf life of 5 or more years in that con- 
dition). Charge current should be 7 to 10% of 
rated cell discharge capacity; thus, for Yardney 
HR-5 cell with rated discharge of 5 A, charge at 
350 to 500 mA. Stop charging when cell voltage 




reaches 2.05 V. If used only for battery charging, 
large filter capacitor can be omitted. — S. Kelly, 



Will Silver-Zinc Replace the Nicad?, 
zine. Holiday issue 1976, p 204-205. 



73 Maga- 




BULK NICAD CHARGER— Can handle up to 20 
AA cells, 20 C cells, and 20 D cells simultane- 
ously, with charging rate determined sepa- 
rately for each type. Single transformer and full- 
wave rectifier feed about 24 VDC to three sep- 
arate regulators. AA-cell regulator uses 100- 
ohm resistor to vary charge rate from 6 mA to 
above 45 mA. C-cell charge-rate range is 24 to 
125 mA, and D-cell range is 60 to 150 mA. Bat- 
teries of each type should be about same state 
of discharge. Batteries are recharged in series 
to avoid need for separate regulator with each 
cell. Trickle-charge switches cut charge rates to 
about 2% of rated normal charge (5 mA for 500- 
mAh AA cells). Transistors are 2N4896 or equiv- 
alent Use heatsinks. All diodes are 1 N4002.— J. 
J. Schultz, A Bulk Ni-Cad Recharger, CO, Dec. 
1977, p 35-36 and 111. 



94 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



CONNECT TO 
POS.TERM. OF 
BATTERY 



+ 13V 




BATTERY MONITOR— Uses CA3097 transistor 
array to provide active elements required for 
driving indicators serving as aural and visual 
warnings of low charge on nicad battery. LED 
remains on until circuit is reset with pushbutton 



(CONNECT TO 
NEG TERM 
OF BATTERY) 

switch. — "Circuit Ideas for RCA Linear ICs," 
RCA Solid State Division, Somerville, NJ, 1977, 
p9. 



To circuit 
being powered 



. Secondary 

cell 






SOLAR-POWER BACKUP— rf solar-cell voltage 
drops 0.2 V below battery voltage, circuit is 
powered by storage cell feeding through for- 
ward-biased OA90 or equivalent germanium 
diode. When solar-cell voltage exceeds that of 
battery, battery is charged by approximately 
constant reverse leakage current through 
diode. Battery can be manganese-alkaline type 
or zinc-silver oxide watch-type cell. — M. Had- 
ley. Automatic Micropower Battery Charger, 
Wireless World, Dec. 1977, p 80. 




D1 

1N5240' 

10 V 



12 V AT 8 A— Charging circuit for lead-acid stor- 
age batteries is not damaged by short-circuits 
or by connecting with wrong battery polarity. 
Battery provides current for charging CI in PUT 
relaxation oscillator. When PUT is fired by CI, 
SCR is turned on and applies charging current 
to battery. Battery voltage increases slightly 
during charge, increasing peak point voltage of 
PUT and making C1 charge to slightly higher 
voltage. When C1 voltage reaches that of zener 
D1 , oscillator stops and charging ceases. R2 sets 
maximum battery voltage between 10 and 14 V 
during charge. — R. J. Haver and B. C. Shiner, 
"Theory, Characteristics and Applications of the 
Programmable Unijunction Transistor," Moto- 
rola, Phoenix, AZ, 1974, AN-527, p 10. 



0.3 ltF/200 V 

<^-r |( 




1 N4001 

— M— 



02 £l.0k 50 hf;^ 

10 W >MSD6150 



r 



i j^1N4001 <10 



10 k 
-^V\r\- 

1.5 k 
— V\Ar- 



' 1.5 k 1.6 k 4 






r 



h: 



THIRD ELECTRODE SENSES FULL CHARGE— 
Circuit is suitable only for special nickel-cad- 
mium batteries in which third electrode has 
been incorporated for use as end-of-charge in- 
dicator. Voltage change at third electrode is suf- 



ficient to provide reliable shutoff signal for 
charger under all conditions of temperature and 
cell variations.— D. A. Zinder, "Fast Charging 
Systems for Ni-Cd Batteries," Motorola, Phoe- 
nix, AZ, 1974, AN-447, p 7. 



9 V I 

t I 

8'3V | 



charger 



:* 



Tfr. 



125|i 



LED VOLTAGE INDICATOR— Circuit shown 
uses LED to indicate, by lighting up, that battery 
has been charged to desired level of 9 V. Circuit 
can be modified for other charging voltages. 
Silicon switching transistor can be used in place 
of more costly thyristor. — P. R. Chatty, Low Bat- 
tery Voltage Indication, Wireless World, April 
1975, p 175. 



BATTERY. CHARGING CIRCUITS 



95 




CR1, CR2 — General-purpose silicon diodes, 1N914 

or equiv. 
Ql — Radio Shack RS2025 transistor. Should be 

mounted on heat sink. 



*-S£E TEXT 



NICAD CHARGER— Switch gives choice of two 
constant-current charge rates. With 10 ohmsfor 
R1, rate is 60 mA, while 200 ohms for R2 gives 
3 mA. Silicon diodes CR1 and CR2 have com- 
bined voltage drop of 1.2 V and emitter-base 



junction of Ql has 0.6- V drop, for net drop of 0.6 
V across R1 or R2. Dividing 0.6 by desired charge 
rate in amperes gives resistance value.— M. Al- 
terman, A Constant-Current Charger for Nicad 
Batteries, QST, March 1977, p 49. 




LED INDICATES LOW VOLTAGE— LED lights 
when output of 9-V rechargeable battery drops 
below minimum acceptable value of 8.3 V, to 
indicate need for recharging. Can also be used 
with transistor radio battery to indicate need for 
replacement. Zener is BZY85 C8V2 rated at 400 
mW, with avalanche point at 7.7 V because of 
low current drawn by circuit. LED can be Hew- 
lett-Packard 5082-4440.— P. C. Parsonage, Low- 
Battery Voltage Indicator, Wireless World, Jan. 
1973, p 31. 




12-V AUTOMATIC— Circuit of Heathkit GP-21 
automatic charger is self-controlling (Ql and 
Q2) and provides protection against shorted or 
reversed battery leads (Q3 and Q4). Zener D8 is 



not standard value, so may be obtainable only 
in Heathkits. D1, D2, and D7 should all be on one 
heatsink.— H. Olson, Battery Chargers Exposed, 
73 Magazine, Nov. 1976, p 98-100 and 102-104. 



VOLTAGE INPUT 
10-13 VOLTS 

^ 



390k 



CI _ 
0.001 



m 

'out 

F 0UT 



NICAD CHARGER FOR AUTO— Voltage doubler 
provides at least 20 V from 12-V auto battery, 
for constant-current charging of 12-V nicads, 
using NE555 timer and two power transistors. 
Doubled voltage drives source current into 
three-terminal current regulator. Switching fre- 




es/ +2R2)CI 



quency of NE555 as MVBR is 1.4 kHz. Charging 
current is set at 50 mA for charging ten 500-mAh 
nicads.— G. Hinkle, Constant-Current Battery 
Charger for Portable Operation, Ham Radio, 
April 1978, p 34-36. 




LED TRICKLE CHARGER— Constant-current 
characteristic of National NSL4944 LED is used 
to advantage in simple haff-wave charger for 
batteries up to 6 V.— "Linear Applications, Vol. 
2," National Semiconductor, Santa Clara, CA, 
1976,AN-153,p2. 



I0A 

-w- 



^-,0-IOA 



DOORBELL OR 
FIL XFMR 



T. 
12 




NICAD ZAPPER— Simple circuit often restores 
dead or defective nicad battery by applying DC 
overvoftage at current up to 10 A for about 3 s. 
Longer treatment may overheat battery and 
make it explode. — Circuits, 73 Magazine, July 
1977, p 35. 



96 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



£ 



SOLAR 
ARRAY 




SOLAR-POWER OVERCHARGE PROTECTION— 
Voltage regulator is connected across solar-cell 
array as shown to prevent damage to storage 
battery by overcharging. Series diode prevents 
array from discharging battery during hours of 
darkness. Regulator does not draw power from 
battery, except for very low current used for 
voltage sampling. Battery can be lead-calcium, 
gelled-electrolyte, or telephone-type wet cells. 
For repeater application described, two Globe 
Union GC12200 40-Ah gelled-electrolyte batter- 
ies were used to provide transmit current of 
1 .07 A and idle current of 12 mA.-T. Handel and 
P. Beauchamp, Solar-Powered Repeater De- 
sign, Ham Radio, Dec. 1978, p 28-33. 




AUTOMATIC SHUTOFF— Prevents overcharg- 
ing and dryout of battery under charge by shut- 
ting off automatically when battery reaches full- 
charge voltage. Accepts wide range of batter- 
ies. Choose rectifying diodes and triacs or SCRs 
to handle maximum charging current desired. 
For initial adjustment, connect fully charged 
battery and adjust charge-stop pot until am- 
meter just drops to zero. — Circuits, 73 Maga- 
zine, July 1977, p 34. 



200W 

II0VLAMP(F0R 3A CHARGE RATE) 

TRIAD (40fl) 

F33U o 




MOTOROLA - HEP 

R0876 

(ON HEAT SINK) 



BASIC 12-V CHARGER— Uses 200-W lamp as 
current-limiting resistor in transformer primary 
circuit. Serves in place of older types of chargers 
using copper-oxide or tungar-bulb rectifiers. — 
H. Olson, Battery Chargers Exposed, 73 Maga- 
zine. Nov. 1976, p 98-100 and 102-104. 



12V BATTERY 



JT- 



TRIAD F33U 



MURALITES 
LAMP 
LIO/20 




-D 6 -IN5399 



14-V MAXIMUM— Circuit accurately limits peak 
output voltage to 14 V, as established by zener 
connected between terminals 3 and 4 oj 
CA3094A programmable opamp. Lamp bright- 



E UT TO BATTERY 
14 V (PEAK) 



ness varies with charging current. Reference 
voltage supply does not drain battery when 
power supply is disconnected. — "Circuit Ideas 
for RCA Linear ICs," RCA Solid State Division, 
Somerville, NJ, 1977, p 19. 




NOTE: 

1. "F" NECESSARY IF LEO IS 
EMPLOYED. 220 OHMS WILL 
PROVIDE NOMINAL BRIGHTNESS. 

2. OUTPUT (PIN 3) WILL SUPPLY 
200 mA TO LOAD. 

NICAD MONITOR — Uses two comparators, flip- 
flop, and power stage all in single NE555 IC. 
When battery voltage drops below 12-V thresh- 
old set by R1 and R2 for 15-V transceiver bat- 
tery, one comparator sets flip-flop and makes 
output at pin 3 go high. IC then supplies up to 
200 mA to LED or other indicator. For other bat- 
tery voltage value, set firing point to about 
three-fourths of fully charged voltage. Since 
battery voltage will show biggest drop when 
transmitting, connect monitor across transmit 
supply only so as to minimize battery drain. — 
A. Woemer, Ni-Cad Lifesaver, 73 Magazine, 
Nov. 1973, p 35-36. 



BATTERY-CHARGING CIRCUITS 



97 



HALF OR 
FULL WAVE 
RECTIFIER 
I5A 
{HEAT SINK) 



f*T ° t | CHARGt 

i p) i2v 



CHARGE LAMP 




OUTPUT 
12-16 VDC 
TO BATTERY 
TERMINALS 



TO TOUCH TONE 
mO OR OTHER 
ACCESSORIES 



ADJUST FOR RELAY 
TRIP ON FULL 
CHARGE BATTERY 



AUTOMATIC SHUTOFF— Charger automati- 
cally turns itself off when 1 2-V auto storage bat- 
tery is fully charged. Setting of 1.5K pot deter- 
mines battery voltage at which zener D1 
conducts, turning on Q2 and pulling in relay that 
disconnects charger. If battery voltage drops 



'MANUAL OVERRIDE 



below threshold, relay automatically connects 
charger again. S2 is closed to bypass automatic 
control when charger itself is to be used as 
power supply.— G. Hinkle, The Smart Charger, 
73 Magazine, Holiday issue 1976, p 110-111. 




NICAD CHARGER— Pot is adjusted to provide 
10% above rated voltage (normal full-charge 
voltage) while keeping charging current below 



25% of maximum. For 10-V 1-Ah battery, set 
voltage at 11 V and current below 250 mA— G. 
E. Zook, F.M., CO, Feb. 1973, p 35-37. 




NICAD CHARGER— Developed for recharging 
small nickel-cadmium batteries used in hand- 
held FM transceivers. Field-effect transistors 
serve as constant-current sources when gate is 
shorted to source. Practically any N-channel 
JFET having drain-to-source current of 8-15 mA 
will work. FETs shown were measured individ- 
ually and grouped to give desired choice of 15- 
ot 50-mA charging currents.— G. K. Shubert, 
FET-Controlled Charger for Small Nicad Batter- 
ies, Ham Radio, Aug. 1975, p 46-47. 



0-10a. 




12-V CHARGER— Heath GP-21 charger uses 
SCR as switch to connect and disconnect bat- 
tery at 120-Hz rate. Voltage at anode of SCR D 7 
goes positive each half-cycle, putting forward 
bias on base of Q, through 1.8K resistor so Q, 
passes current through D 5 to gate of D 7 to turn 



it on for part of half -cycle and charge battery. D, 
stays on until voltage across it drops to zero. 
When battery has charged to 13.4 V, charging 
stops automatically. Rest of circuit protects 
against battery polarity reversal and accidental 



shorting of output leads. Special 12.8-V zener 
can be replaced by selected 1IM4742 and for- 
ward-biased 1N4002. — H. Olson, We Don't 
Charge Nothin' but Batteries!, CO, Feb. 1976, p 
25-28 and 69. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Tl 
SEE TEXT 



01 

SOV, 6A 
BRIDGE 
RECTIFIER 




* T2 SPRAGUE 
II Z 2000 



R3 
22 K 



Rl 

911 

30W 



R2 
9ft 

Sow 

2*-VW- 



3c< o 3 

"A" "6" 

ROTARY SWITCH 





^03 
1 FSCR 

"*■ 2NI77I 



R4 
IK 

RS 
2.5K 

POT. 

R5 
2.7 K 




UJT CHARGER FOR 12 V— Keeps 12-V auto 
storage battery fully charged, for immediate 
standby use when AC power fails. Power trans- 
former secondary can be 14 to 24 V, rated at 
about 3 A. Two-gang rotary switch gives choice 
of three charging rates. Pulse transformer T2 is 
small audio transformer rewound to have 1:1 



turns ratio and about 20 ohms resistance, or can 
be regular SCR trigger transformer. UJT relax- 
ation oscillator stops when upper voltage limit 
for battery is reached, as set by pot R6. If oscil- 
lator fails to start, reverse one of pulse trans- 
former windings.— F. J. Piraino, Failsafe Super 
Charger, 73 Magazine, Holiday issue 1976, p 49. 



22k 



IN 
4746 




-0+18V 



-Ocomi 



-0-18V 



18-V MONITOR — Circuit turns on LED when 
±18 V battery pack discharges to predeter- 
mined low level, while drawing less than 1 mA 
when LED is off. Zener is reverse-biased for nor- 
mal operating range of battery. When lower 
limit is reached, zener loses control and Q, be- 
comes forward-biased, turning on LED or other 
signal device to indicate need for replacement 
or recharging.— W. Denison and Y. Rich, Battery 
Monitor Is Efficient, yet Simple, EDN Magazine, 
Oct. 5, 1974, p 76. 



-O +11Vdc 




FLASHING LED FOR LOW BATTERY— Devel- supply. Instrument must then be plugged into IQ,, so blink clock (such as low-frequency TTL- 



oped for use in portable battery-operated test 
instrument to provide visual indication that de- 
pletion level has been reached for series ar- 
rangement of 24 nickel-cadmium cells provid- 
ing 32.5 VDC for regulator of bipolar 11-V 



AC line for recharging of batteries. Voltage 
across B, (nominally 32.5 V) is sensed by Rt-R 4 
and D,. When level drops 24.1 V, opamp com- 
parator output goes positive and enables gate 



level oscillator) makes LED flash. Audible alarm 
is optional. — R. T. Warner, Monitor NiCad's 
with This Low-Battery Detector, EDN Maga- 
zine, April 20, 1976, p 1 12 and 1 14. 



BATTERY-CHARGING CIRCUITS 



99 




CONSTANT-CURRENT NICAD CHARGER— 
Constant current is obtained from voltage reg- 
ulator by floating common line and connecting 
R1 from output to common terminal. Regulator 
then tries to furnish fixed voltage across R1. 
Input voltage must be greater than full-charge 
battery voltage plus 5 V (for 5-V regulator) plus 



rh 



2 V (overhead voltage). Changing R1 varies 
charging current. If R1 is 50 ohms and V is 5 V, 
constant current is 50 mA through nicad being 
charged.— G. Hinkle, Constant-Current Battery 
Charger for Portable Operation, Ham Radio, 
April 1978, p 34-36. 




NICAD CHARGER— Regulated charger circuit 
will handle variable load from 1 to 18 nicad cells. 
Current-limiting action holds charging current 
within 1 to 2 mA of optimum value (about one- 
tenth of rated ampere-hour capacity) from to 
24 V. Q1 should have power rating equal to 



twice supply voltage multiplied by current-limit 
value. If charging 450-mAh penlight cells, 
charge current is 45 mA and transistor should 
be 2 W.— A. G. Evans, Regulated Nicad Charger, 
73 Magazine, June 1977, p 117. 



Iheavy overcast 



CELL SELECTOR 
('BRIGHT SUN 



* SOLAR 
CELLS 



D2> 

-w- 



RECHARSABLE -^=- 
CELL ^^ 



~(N34 OR 

, EQUIVALENT 



SOLAR-ENERGY CHARGER— Single solar cell 
on bright day delivers 0.5 V at 50 mA, so three 
cells are used in bright sun to recharge second- 
ary cell. Switch permits use of additional solar 
cells on cloudy days. Solar cells can be Radio 
Shack 276-128.— J. Rice, Charging Batteries 
with Solar Energy, QST, Sept. 1978, p 37. 



FAIRCHILD 
FDC 810 



FLOAT VOLTAGE 
SET 



TRIAD 

F40X 

BLK RED 




k 



IKV 



BLK RED 



12-V FOR GELLED-ELECTROLYTE— Designed 
to charge 12-V 3-Ah gelled-electrolyte battery 
such as Elpower EP1230A at maximum of 0.45 
A until battery reaches 14 V, then at constant 
voltage until charge current drops to 0.04 A. 
Charger is then automatically switched to float 




IN4002(2) 



, 0.IA+I9V 
i > — vvv • 



status that maintains 2.2 V per cell or 13.2 V for 
battery. Circuit is constant-voltage regulator 
with current limiting as designed around Na- 
tional LM305H, with PNP/NPN transistor pair to 
increase current capability. Circuit above 



dashed line is added to standard regulator to 
meet special charging requirement. Article cov- 
ers operation and use of circuit in detail.— H. 
Olson, Battery Chargers Exposed, 73 Magazine, 
Nov. 1976, p 98-100 and 102-104. 



100 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




©© 



NICAD CHARGE CONTROL— Prevents double- 
charging if someone forgets to turn off 24-h 
time clock after recommended 16-h charge pe- 
riod. Nicad devices with built-in chargers are 
plugged into jacks J,-J 3 , and timer dial is ad- 
vanced until clock switch is triggered. Neon 



lamp NE, should now come on. Momentary 
pushbutton switch S is pushed to energize relay 
K and start charge. When timer goes off, K re- 
leases to end charge.— M. Katz, Battery Charge 
Monitor, CQ, July 1976, p 27. 



4 VOLT 40 mA 
(SYLVANIA < ES) 



n^-n 




GELLED-ELECTROLYTE BATTERIES— Con- 
stant-voltage charger for Globe-Union 12-V 
gelled-electrolyte storage batteries can provide 
either fast or float charging. Constant voltage 
is maintained by series power transistor and 



series-connected zeners. Output voltage is 13.8 
V for float charging and 14.4 V for fast charg- 
ing.— E. Noll, Storage-Battery QRP Power, Ham 
Radio, Oct. 1974, p 56-61. 



CHAPTER 9 

Burglar Alarm Circuits 



For auto, home, office, and factory installations. Sensors include contact- 
making, contact-breaking, photoelectric, infrared, Doppler, and sound- 
actuated devices that trigger circuit immediately or after adjustable delay for 
driving alarm horn, siren, tone generator, pager, or silent transmitter. Some 
circuits have automatic shutoff of alarm after fixed operating time as required 
for auto alarms in some states. See also Protection (for electronic door locks) 
and Siren chapters. 



47 k 
-WW 



lo lo lo lo lo 




push to on 



MANUAL 

RESET 

S3 



FIVE-INDICATOR ALARM— Single five-transis- 
tor IC uses NPN structures on P-type substrate 
as PNPN silicon controlled switches having 
common connection for anode (substrate). 
Relay serving as anode load is energized for ac- 
tuating alarm if any of the SCS pushbutton 
switches is closed. Corresponding lamp is en- 
ergized to identify door or window at which 
sensor switch has been closed by act of in- 
truder. Alarm remains on until reset by inter- 
rupting power supply. Power drain on standby 
is negligible because SCSs act as open circuits 
until triggered, permitting use of batteries for 
supply. Two or more ICs may be added to get 
more channels. — H. S. Kothari, Alarm System 
with Position Indication, Wireless World, Feb. 
1976, p 77. 







ENTRY-DELAY ALARM— First 555 timer pro- 
vides delay of about 20 s after triggering by sen- 
sor before alarm bell is energized, to allow thief 
to be caught inside house or give owner time to 
enter and shut off alarm. Alarm then rings for 




about 60 s under control of timer U2. Alarm pe- 
riod was set short to attract attention without 
unduly annoying neighbors. — J. D. Arnold, A 
Low-Cost Burglar Alarm for Home or Car, QST, 
June 1978, p 35-36. 



PTT ON 
MICROPHONE 

SCR LATCH — Turns on mobile transceiver or 
other mobile equipment when power is applied, 
if external circuit is broken when equipment is 
stolen. Transmitter will then put unmodulated 
carrier on air even with PTT switch discon- 
nected or off, for tracing with radio direction 
finder. If added components are carefully con- 
cealed in equipment and new external wiring is 
worked into existing wiring harness, few 
thieves will be able to locate trouble. External 
wires are run under dash so thief must cut them 
to get out equipment. PTT relay should have 
protective diode. SCR is 100 PIV, 1 A, but HEP 
R1003 or R1217 can also be used.— E. Noll, Cir- 
cuits and Techniques, Ham Radio, April 1976, p 
40-43. 



101 



102 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



sv o 



FROM ALARM 
1RANSOUCERS 



FROM ALARM 
TRANSDUCERS 




ALARM-SIGNAL DETECTOR— Texas Instru- 
ments SN754B4B dual peripheral positive-NOR 
driver energizes alarm relay when alarm signal 
is received from any one of four different alarm 
transducers. — 'The Linear and Interface Cir- 
cuits Data Book for Design Engineers," Texas 
Instruments, Dallas, TX, 1973, p 10-66. 



+13 v c, 

100 /.F 



AURAL INDICATOR— Provides attention-get- 
ting chirp sound, warble, or continuous tone 
when turned on by high input from burglar- 
alarm sensor circuit. Second section of 556 
timer provides optional frequency modulation 
of basic tone to give warbling effect. Chirp is 
achieved by gating tone oscillator on only dur- 
ing high states of warble oscillator. Aural sen- 
sitivity is maximum in range of 1-2 kHz, set by 
value of Re. — W. G. Jung, "IC Timer Cookbook," 
Howard W. Sams, Indianapolis, IN, 1977, p 232- 
235. 



_r 



Enable 
Input 

On 

OH 



V+ 
I 

A, OUT 

SS6 

A 

GND 



't 




-I WW 



00 kn 






1N4O01 




Warble 
Depth 



svo 



FROM ALARM 
TRANSDUCERS 



FROM ALARM 
TRANSDUCERS 




ALARM DETECTOR— National DS75454 dual 
peripheral NOR driver operating from single 5- 
V supply energizes alarm relay when one of 
alarm transducers for either section delivers 
logic signal as result of intruder action. — "In- 
terface Databook," National Semiconductor, 
Santa Clara, CA, 1978, p 3-20-3-30. 



BURGLAR ALARM CIRCUITS 



103 



T_ 



Transmitter 

and 

tone generator 



12v. 



^rT< 




To door 
switches 



SILENT ALARM— When thief opens car door, 
relays K, and K 2 activate tone-modulated trans- 
mitter, which can be any legal combination of 
power, frequency, and antenna. A few milli- 
watts of power should be adequate. Thief hears 
nothing, but owner is alerted via portable re- 
ceiver tuned to transmitter frequency. Trans- 
mitter remains on about 15 s (determined by R, 
and CO after door is closed until NES55 times 
out and removes power from transistor. Use 
any NPN transistor having adequate current rat- 
ing for relay. If alarm is provided with its own 
battery and whip antenna, it cannot be disabled 
from outside of car.— A. Day, Soundless Mobile 
Alarm, CO, April 1977, p 11. 




SONALERT 



CAR-THEFT ALARM— Alarm remains on even if 
signal from car door switch or other sensor is 
only momentary, so relay is wired to be self- 
latching until keyswttch SI is turned off. Use 
hood locks or hood-opening sensors to prevent 
thief from disabling alarm by cutting battery 
cable. Circuit includes time delay of 6 s for en- 
tering car and shutting off alarm, to avoid need 
for external keyswttch. Sonalert makes loud 
tone during 6-s delay period to remind driver 
that alarm needs to be turned off. At end of 6 s, 
Sonalert stops and much louder bell Is ener- 
gized to further discourage intruder. — J. Paw- 
Ian, The Smart Alarm, 73 Magazine, June 1975, 
p 37-41. 



12 V 
O 



1meg 



ARM 
DISARM 
SWITCH 



14 



1/2 NE556 5 



10 jifd 



f— o >o 

TO 

HORN 

O RELAY O 



'N4920 J ' 



Inieg 



1/2 NE556 



ALL RESISTOR VALUES ARE IN OHMS 



T 



DOOR 
SWITCHES 



~ lO^fd 




DELAYED ALARM— When normally closed arm/ 
disarm switch is opened, first section of NE556 
dual timer starts its timing cycle. After delay to 
allow for entry or exit, pin 5 goes low to ener- 



SHORT DURATION TIMERS ARE NEEDED 
TO ALLOW ENTRY AND EXIT 

gize alarm circuit. Now, as long as all door for owner to enter car, and hom is sounded un- 

switches are closed, PNP transistor is kept off less owner closes arm/disarm switch within 

because pin 9 is high. When any door switch is delay time. — "Signetics Analog Data Manual," 

opened, transistor turns on after normal delay Signetics, Sunnyvale, CA, 1977, p 724-725. 



104 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




Ohorn 



FAIL-SAFE TIMED ALARM— Horn comes on 
about 30 s after intruder closes door switch by 
opening car door. Delay is produced by NE555 
timer to allow driver to close door after entering 
or leaving. Thief must keep door open to get leg 
room for removing equipment under dash. 
Diodes are 50-PIV 1-A silicon. K1 has 12-V coil. 
Alarm is set at all times. SI is normally closed 
pushbutton type in door jam. Opening SI starts 
timer, and closing it resets alarm. — R. S. 
Harvey, Junk Box Foils Thieves, QST, Sept. 
1977, p 50-51. 



v D d 



Clock register 




^4 4001 



°c ry~ < 1/4 4001 



Current detectors 

3/ 4 3900 quod 
operational amplifier 



Output to 
remote units 



\ 4011 



Ho q, 

r a 




V£ 4011 



V-AAA/ *— 

" 7 ° k 470n 

Display flashing oscillator 

MULTIPLEXED BURGLAR ALARM— Multiplex- 
ing technique provides for detection of state of 
up to 10 sensors, with immediate identification 
and location of activated sensor. Only one pair 
of wires runs from control unit to paralleled re- 
mote sensor circuits, one of which is shown at 
upper right. Each sensor location uses different 
output from one to zero. Multiplexer circuit is 



2 out of 10 latches 
and display drivers 



based on 4017 decade counter having 10 indi- 
vidual outputs, to give signals in 10 time slots. 
Power supply rail is used to reset counter. Clock 
line is eliminated by switching supply line as 
square wave. Sensor indication line is elimi- 
nated by detecting power supply current drain. 
Control unit uses oscillator and shift register to 
generate clocking waveforms. 3900 quad 



opamp converts sensor line current to logic lev- 
els for clocking by master 401 7 to control 10 out- 
put latches and display driver. Two consecutive 
sensor-open signals are required to activate 
alarm, minimizing false alarms by interference 
pulses. — R. J. Chance, Multiplexed Alarm, 
Wireless World, Nov. 1978, p 73-74. 



BURGLAR ALARM CIRCUITS 



105 



v+ 





+9V, BURGESS 246 
SUITABLE 



H 

s, 

Reset 



D, 
1N914 



C, _L 
2mF 



R 2 < < R : 

lMn? Q, ?100kfi 
2N3904 



I— DIS 





OPENING THIS CONTACT 
SETS OFF ALARM-THIS 
IS A FAIL-SAFE FEATURE. 

CIRCUIT-BREAKING ALARM— Operates from 
small 9-V battery, making it independent of AC 
power failure. Opening of switch or equivalent 
breaking of foil conductor removes ground from 
base of transistor, to energize alarm. — Circuits, 
73 Magazine, April 1973, p 132. 



Tamper 
Switches 



o 

i 



Defeat 



WINDOW-FOIL ALARM— Combination of 
power-up mono MVBR and latch, using both 
sections of 556 timer, drives output line high 
when sensor circuit is opened at door or win- 
dow switch or by breaking foil on glass. Once 
alarm is triggered, reclosing of sensor has no 



effect; S, must be closed momentarily after re- 
storing sensor circuit to turn alarm off. Circuit 
includes 22-s power-up delay that prevents trig- 
gering of alarm when it is first turned on. — W. 
G. Jung, "IC Timer Cookbook," Howard W. 
Sams, Indianapolis, IN, 1977, p 231-232. 



+9V main supply 



+9V main supply 




+9V separate supply 



R22M R23rl 
8.2M 150M 



D 



30on 

min 







R2t 
10k C 



R2S 
27k 



TR2 
BC109 

R26 
10kO 



© 



LOW-CURRENT INTRUDER ALARM— Use of 
programmable juA776 opamps reduces standby 
current of infrared alarm to 300 juA, permitting 
operation from small rechargeable cells. Detec- 
tor is Mullard RPY86 that responds only to 
wavelengths above 6 fim, making it immune to 



sunlight and backgrounds intermittently illu- 
minated by sun. Low-cost mirror is used instead 
of lens to concentrate infrared radiation on de- 
tector. R„ is chosen to make input to first opamp 
between 2 and 6 V. Circuit energizes alarm relay 



R L only when incident radiation is changed by 
movement of intruder in monitored space. — 
"Ceramic Pyroelectric Infrared Detectors," Mul- 
lard, London, 1978, Technical Note 79, TP1664, 
p8. 



106 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



rft 




SI RESET SWITCH 
NORMALLY CLOSED 
(OPTIONAL) 



LIGHT-INTERRUPTION DETECTOR— Use of 
SCR as regenerative amplifier rather than as 
switch gives extremely high sensitivity to very 
slight reductions in light reaching photoresis- 
tor. Requires no light source or accurately 
aligned light-beam optics. In typical application 
as burglar alarm, light shining through window 
from streetlight provides sufficient ambient il- 
lumination so any movement of intruder within 
10 feet of unit will energize Sonalert alarm. Sen- 
sitivity control R4 is adjusted so SCR receives 
positive pulses from AC line, but their ampli- 



tude is not quite enough to start regenerative 
action of SCR. Reduction in light then increases 
resistance of photoresistor enough to raise 
level of gate pulses for SCR, starting regenera- 
tive amplification that energizes relay. Use Mal- 
lory SC-628P Sonalert which produces pulsed 
2500-Hz sound. With S2 open, alarm stops 
when changes in light cease. With S2 closed, 
alarm is latched on and S1 must be opened to 
stop sound. — R. F. Graf and G. J. Whalen, 'The 
Build-It Book of Safety Electronics," Howard W. 
Sams, Indianapolis, IN, 1976, p 7-12. 




LATCHING ALARM— Closed-circuit alarm 
drawing only 130 j*A of standby current from 
battery is turned on by opening sensor switch 
or cutting wire. Automatic latching contacts on 
relay prevent burglar or intruder from deacti- 
vating alarm by resetting sensor switch. Relay 
is Radio Shack 275-004. Sensor can be foil strip 
around window subject to breakage. — F. M. 
Mims, 'Transistor Projects, Vol. 3," Radio 
Shack, Fort Worth, TX, 1975, p 75-86. 




Adjust to give 
correct voltage fi 
Gunn device 



Voltage gain about 50 



CU 
100 nF 




50Hz twin -tee 
band slop filter 



bratof for automatic 
zero reset 



* lOnF capacitors C5.C9, and CI3 should be connected 
as close as possible between pins 4 and 7 of ICs 

A For 60Hz use 27kn for R21, R23, and 12kn for R22 



MICROWAVE DOPPLER INTRUSION ALARM— 
Mullard CL8960 X-band Doppler radar module 
detects movement of remote target by moni- 
toring Doppler shift in microwave radiation re- 
flected from target. Module consists of Gunn 
oscillator cavity producing energy to be ra- 
diated, mounted alongside mixer cavity that 



combines reflected energy with sample of os- 
cillator signal. Transmitted frequency is 10.7 
GHz. Doppler change is about 31 Hz for relative 
velocity of 0.45 m/s (1 mph) of relative velocity 
between object and module, giving AF output 
for velocities up to 400 mph. Filtered AF is ap- 
plied through diode pump to trigger of silicon 



controlled switch TR3 that makes contacts of 
reed relay open for about 1 s. Relay action is re- 
peated as long as intruder is in monitored area. 
Report covers circuit operation in detail. — J. E. 
Saw, "Microwave Doppler Intruder Alarms," 
Mullard, London, 1976, Technical Information 
36, TP1570, p 6. 



BURGLAR ALARM CIRCUITS 



107 




V 270 n 



Bl-=-9V 



ATTACH LEAD TO 

MOUNTING SCREW 

OR METAL BODY 

Of SI 




NOTE: TOUCHING MOUNTING SCREW OF SI AND CASE OF S2 
COMMUTATES SCR BY MOMENTARILY ENERGIZING Ql 



HOTEL-ROOM ALARM— Alarm mounted in 
flashlight-shaped cylinder is positioned on floor 
inside hotel room in such a way that it is 
knocked over by intruder opening door. Mer- 
cury switch S2 then triggers SCR and activates 
Mallory SC-628P pulsed Son alert alarm. Circuit 
latches on and can be turned off only by use of 
Darlington-amplifier touch switch. Connection 
from base of Darlington to positive terminal of 
battery must be made through fingertips as 



shown by dashed line in order to silence alarm. 
Once silenced, SI can be opened to disconnect 
latch so alarm can be moved. Other applications 
include protection of unattended luggage. C1 is 
0.1 pF, R1 is 1 megohm, R2 is IK, R3 is 39K, and 
S2 is mercury element removed from GE mer- 
cury toggle switch. — R. F. Graf and G. J. 
Whalen, "The Build-It Book of Safety Electron- 
ics," Howard W. Sams, Indianapolis, IN, 1976, p 
19-24. 



To other circuits, 
if used. 



VISUAL INDICATOR— When circuit is activated 
by high output of burglar alarm circuit, 555 
timer operating as very low frequency MVBR 
makes LED, flash on and off during alarm con- 
dition. Alternate connection of LED, to V+ holds 
LED, on for standby while flashing it during 
alarm. Oscillator output is also available for 
other uses if desired. Indicator can be located 
remotely from alarm. — W. G. Jung, "IC Timer 
Cookbook," Howard W. Sams, Indianapolis, IN, 
1977, p 232-235. 



v.m 



DOME f—i I 
LIGHT Sn 




/77 /77 /77 



NOTE: CONNECT DOME LIGHT CIRCUIT 
TO O OR @ AS APPROPRIATE, 
BUT NOT BOTH. 



5-min SHUTOFF— Vehicle intrusion alarm shuts not affected by subsequent opening or closing Ql and relay, as well as automatic shutoff delay, 

off automatically in about 5 min after being trig- of doors. System uses two CMOS CD4001 AE Article gives construction details and layout for 

gored, as required by law in some states. Drain quad two-input NOR gates for switching logic. printed-circurt board.— W. J. Prudhomme, Ve- 

on battery is negligible until alarm is set off by IC1 provides sensor interface, latch, and entry/ hide Security Systems, 73 Magazine, Oct. 1977, 

intruder. Once triggered, operation sequence is exit time delays. IC2 provides output through p 122-125. 



108 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




•O TO HORN RELAY 



CURRENT-DRAIN SENSOR— Current drawn by 
dome light when door is open or by ignition 
when turned on triggers current-sensing stages 
Q1 and Q2 to start 555 timer and apply power 
to horn relay. Initial 15-s delay in sounding horn 
allows owner to enter car and open hidden 
switch S1 to deactivate alarm. If SI is not 
opened during delay interval, horn sounds for 
about 90 s, then circuit automatically resets it- 
self. C5 and R5 control duration of initial 15-s 
delay. C2 and R4 control total time that horn 
sounds. — R. F. Graf and G. J. Whalen, "The 
Build-It Book of Safety Electronics," Howard W. 
Sams, Indianapolis, IN, 1976, p 57-62. 



ENABLE ALARM 
\OFF 



SWITCH 
CLOSURE" 
TO GROUND 
INPUT 



PULSED-HORN ALARM— Two CMOS packages 
incorporate multiple time delays to improve 
convenience and effectiveness of auto intrusion 
alarm. R1C1 gives 30-s delay for arming alarm 
after it is turned on by switch concealed inside 
car, to let driver get out of car. R2C2 gives 15-s 
delay before alarm sounds after door is opened. 



ALTERNATE 
OUTPUT CIRCUIT 
/TO HORN RELAY 




TO HORN RELAY 



to allow driver to get back in car again and dis- 
able alarm. R3C3 turns off alarm in 300 s and re- 
sets alarm system for next intrusion. Car hom 
is pulsed 60 times per minute, so alarm would 
not be confused with stuck horn. Article tells 



how circuit works and gives detailed instruc- 
tions for installation and connection to door and 
trunk switches. — G. Hinkle, Give the Hambur- 
glar Heart Failure, 73 Magazine, Feb. 1977, p 36- 
37. 



R12 

i7kfl 




Preamplifier 



INTRUDER ALARM— Input is from Milliard 
RPY86 infrared detector responding to wave- 
lengths above 6 jtm, making it immune to sun- 
light and backgrounds intermittently illumi- 
nated by sun. Output signal is produced only 
when incident radiation is changed by move- 



Diode pump 
First trigger 



Second trigger ond relay drive 



ment of intruder in monitored space. Mirrors 
rather than lenses concentrate incident radia- 
tion on detector because mirrors do not require 
high-quality surface finish. Preamp is followed 
by two amplifier stages, with R10 varying gain 
of second stage between 10 and 100. Band- 



width is 0.3-10 Hz. First trigger, having thresh- 
old of about 1 V, drives second trigger through 
diode pump to energize alarm relay when in- 
truder is present. — "Ceramic Pyroelectric In- 
frared Detectors," Mullard, London, 1978, Tech- 
nical Note 79, TP1664, p 8. 



BURGLAR ALARM CIRCUITS 



109 




CONVENIENCE AC OUTLET 
TO LAMP & BELL 

OPEN-CIRCUIT ALARM— Closing of door or 
window switch sensor or closing of normally 
open panic-button switch at bedside and other 
strategic locations in home trips alarm that 
sounds loud bell and flashes bright light on and 
off. Sensor shorts control winding of K1, allow- 
ing K1 to drop out and apply line voltage to 
alarm circuit. One AC path is through D5 which 
rectifies AC for energizing DC latch relay K2 to 
short sensor lines even though initiating sensor 
has opened. Simultaneously, AC is applied to 
diode bridge having SCR between DC legs. C2 
starts charging through R2 and R4, and C3 
charges through R3. When voltage across C3 



reaches about 90 VDC, it fires neon and C3 dis- 
charges into gate of SCR. Full line voltage is 
then applied to lamp and bell plugged into load 
outlets. When C2 drops below holding current, 
SCR turns off during next AC cycle and load 
goes off until neon fires again. Setting of 5K pot 
R4 gives range of 15-80 flashes and horn pulses 
per second. To stop alarm, open SPST switch 
momentarily. — R. F. Graf and G. J. Whalen, 
'The Build-It Book of Safety Electronics," How- 
ard W. Sams, Indianapolis, IN, 1976, p 75-80. 




L BASIC J 

~ ALARM ~ 



WIRE-CUTTING ALARM— SCR normally acts as 
open circuit in series with 12-VDC alarm relay 
because grid is made negative by voltage di- 
vider consisting of 100K in series with 500 
ohms. If ground on 500-ohm resistor is re- 
moved, as by removal of tape player or CB set 
from car by thief, gate becomes more positive 
and SCR conducts, to energize relay, sound 
horn, and make headlights shine brightly. Ad- 
ditional triggering SCRs or alarm switches can 
be added as shown outside of dashed area for 
basic alarm. — A. Szablak, Another Burglar 
Alarm, 73 Magazine, May 1974, p 45-46. 



SOUND-ACTIVATED SWITCH— Can be used as 
sensor for burglar alarm or for turning on sur- 
veillance tape recorder to monitor conversa- 
tions. R 8 is adjusted to give desired sensitivity 
at which A 2 triggers switch Q, to provide 200- 
mA load current and turn on indicator LED. First 
section of LM339 quad comparator serves as 
amplifier and detector providing gain of 100. 
Second comparator compares DC output of first 
with reference level selected by R 8 . — D. R. Mor- 
gan, Sound Turns Switch On, BDN Magazine, 
Aug. 5, 1978, p 82 and 84. 




T0.1 «F 

-± * — " 



rSA I 2N3904 4.7K 

Q^nvT 1 



v i € Pr s n 

'T^lfiF >47K S68K 'T* gg 



!^D30 




VCH 
4 — •-•. *I2 BATT 



♦ SW 6ND I*I5) 



ALARM DRIVES PAGING BEEPER— Complete 
protection of vehicle is provided by multiplicity 
of door-switch, mat-switch, vibration, motion, 
and other sensors connected to common sen- 
sor input of alarm switching circuit that controls 
radio pager, 1-W GE Voice Command II trans- 



mitter operating around 147 MHz, 100-W elec- 
tronic siren, and power horns. Closing of con- 
tacts in any sensor grounds common input 
(assuming keylock switch has been closed to 
arm circuit by applying +12 V), applying power 
to siren and pager system. Range is about 1 mi 



for Motorola Pageboy II cigarette-pack-size 
pager receiver. Article describes construction, 
operation, and installation in detail and gives 
complete circuit of pager. — J. Crawford, Build 
a Beeper Alarm, 73 Magazine, Oct. 1977, p 68- 
77. 



no 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



DOPPLER BURGLAR ALARM— Small radar 
transmitter operating at 10.687 GHz fills pro- 
tected area with radio waves. Waves reflected 
from stationary objects are ignored by receiver, 
while waves undergoing Doppler shift in fre- 
quency by reflection from moving object such 
as intruder are selectively amplified for trigger- 
ing of alarm. Single waveguide section is di- 
vided into two cavities, each having Gunn 
diode; transmitter cavity feeds points A and B 
of transmitter TR7-IC3, and other cavity feeds 
points C and D of amplifier that drives alarm 
relay. Article covers construction and operation 



of circuit and gives sources (British) for parts 
and construction kits. Opamps are SN72748 or 
equivalent, IC 3 is /xA723 or equivalent, Tr,-Tr 3 
are ZTX500 or equivalent, Tr 4 -Tr 6 are ZTX302 or 
equivalent, Tr 7 is 3055, D,-D 8 are 1N4001 or 
equivalent, D 9 -D 10 are 1N914, SCR, is TIC44 or 
equivalent, Z,-Z 2 are BZY88-C8V2, relay is 18-V 
with IK coil, Doppler module is Mullard CL8960 
or equivalent, and self-oscillating mixer for re- 
ceiver is Mullard CL8630S or equivalent. Alarm 
stays on until reset by appropriate switch. — M. 
W. Hosking, Microwave Intruder Alarm, Wire- 
less World, July 1977, p 36-39. 



o- 
C 



C lT ^2 T 10k 







t " 

Yl Y 2 



"lc, 6 
T »u 



To 
transmitter 




OOV 



* e e «■ > * t—aw-vw— *> 

C 23 lOOn C 24 100n 1 
II " II » 2 



jismsswuL 



KjlAflAAMJULr 



-O- 



'• i iTnro" ffoo " o " ffg ooa8ao"o'o'o"ao'a"a'o"> 



, \j 



BURGLAR ALARM CIRCUITS 



111 



SCR 



SWITCHED 
6-I5VDC C— 
SUPPLY 



-®e t — p- 





BEEPER — Intermittent alarm using 555 timer 
can be set to energize horn, lights, or other sig- 
naling device at any desired interval when 
tripped. When used on auto, sound cannot be 
mistaken for stuck horn. Choose SCR rating to 
handle current drawn by relay and timer. If 
alarm draws less than 200 mA, relay is not 
needed. — W. Pinner, Alarm! Alarml Alarm!, 73 
Magazine, Feb. 1976, p 138-139. 



OPEN/SHORT/GROUND ALARM— Pin 6 of 
CA3094 IC is high for no-alarm condition. When 
any one sensor line is open, is shorted to other 
line, or is shorted to ground, output of IC goes 
low and resulting output current serves for ac- 
tivating alarm system. — E. M. Noll, "Linear IC 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 1974, p 316-317. 



*^J 



LATCH-ON ALARM— Alarm cannot be shut off 
for 12 s, with delay provided by IC, connected 
as mono, even if trip condition is immediately 
removed. Developed for home, garage, and 
auto burglar alarm systems having any number 
of trip switches. Circuit is self-resetting after 
delay interval, has high resistance to false 
alarms other than direct entry, and operates 




even when AC power fails. Circuit is latched 
through contacts of K,. On standby, battery 
drain is zero. — J. D. Long, Burglar Alarm Is Ef- 
fective, yet Simple and Inexpensive, EON Mag- 
azine, Dec. 20, 1974, p 50-51. 



AUDIO 
ALARM TRIPPED 
OUTPUT 

l~1kHz) 



CHAPTER 10 

Capacitance Measuring Circuits 



Timers, bridges, dip meters, counters, phase-locked loops, and 
microprocessors drive meters, digital displays, or audible indicators giving 
values of capacitors. 



FN0507 




FND507 




FND507 




FND507 






















METER RANGE SWITCH: 
POSITION A: 10- 1,000 pF 
B: 1- 1,000 nF 
C: 1 - I.OOOjuF 
GATES G, - G 4 : %7400 






















9357B 




9357B 


9357B 




9357B 










































93175 




93175 




93175 




93175 
















































i 














i 




" 






i 










































93176 






93176 






93176 






93176 






































i 








"i_r 

CLEAR 














_n_ 


~i_r 




93176 Q D 




93176 Q D 






* 




LATCH 


CLOCK 























DISPLAYS 



DECODER- 
DRIVERS 



4-BIT 
LATCHES 



DECADE 
COUNTERS 



DUMMY 
COUNTERS 




5V 



:i0jiF 



other as clock driving digital counter having 
~ Fail-child FND507 4-digit display. Arrangement ~ 

10 pF TO 1000 /*F DIGITAL — Uses 555 timers as gives good accuracy without use of crystal os- Build Accurate Capacitance Meter, Electronics, 

free-running oscillators, one for gating and cillator. — W. H. Wang, Low-Cost Oscillators May 26, 1977, p 127 and 129. 



112 



CAPACITANCE MEASURING CIRCUITS 



113 



CI4-74400 PINI4- + 5V PIN7-GND 



..COUNTER 
INPUT 

40MHI (I) OR 
400KHl(2) 



ZERO ADJ- BOURNS 

38S2A-2B2-50IA 
500ft 
ZERO PREADJ- BOURNS 

3006P-I-I02 IK 




1 pF TO 1 fiF — Presents instantly in digital form 
the value of unknown capacitor, in ranges of 1- 
9999 pF and 1-999.9 nF. Four digits are dis- 
played, with leading-zero suppression and ov- 
erflow indicator. Accuracy is better than 0.1% 
of full range ± 1 digit for higher values in both 
ranges. Mono MVBR IC21 produces pulse 
whose length is directly proportional to value 
of C x plus about 980-pF total in C F . This pulse 
enables gate IC14D whose output goes to 
counter. Oscillator 02, buffer 03, dividers IC15 
and IC16, and gates IC14 together give 40-MHz 
(range 1} or 400-kHz (range 2) pulses that are 
counted while IC21 holds IC14D open. Article 
covers construction in detail. — I. M. Chladek, 
Build This Digital Capacity Meter, 73 Magazine, 
Jan. 1976, p 70-78. 



osc. 



DIVIDER CHAIN 



C WITH VOM — TTL-derived square-wave gen- 
erator U1 charges unknown capacitor C, to 
about 3.5 V at 285 kHz when using 150-mA scale 
of Heath MM-1 volt-ohm-milliammeter. to give 
150-pF full-scale range. Larger values of capac- 
itance are read by decreasing frequency with 
7490 decade dividers. Use Mallory PTC401 for 
CR1-CR4. T1 is 6.3-VAC filament transformer. S2 
restores normal VOM functions. Article gives 
design equations. — K. H. Cavcey, Read Capaci- 
tance with Your VOM, QST, Dec. 1975, p 36-37. 



I 1 -/ 12 ) U1C />*? U2 12-1 U3 12. 1 U4 12 

2200 UI£_y ^5 7490 ~f~ 7490 ~ t~ 7490 ~ 




114 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



~*yC— 



—y£— 



— y£— 



CX 

r-)|- 



" 



f»e 



CR2 

-w— t — f 



CRI 





Total 






Range 


R 


C 


Frequency 


0-100 pF 


15k 


5pF 


1100 kHz 


0-1000 pF 


31k 


100 pF 


112 kHz 


.01 uF 


36k 


1500pF 


11.2 kHz 


.1 uF 


45 k 


.012 uF 


1.170 kHz 


1 uF 


45k 


.1 uF 


109 Hz 



T I y 



5 pF TO 1 /*F — Consists of an oscillator using 
two gates from CD4011 quad NAND gate, sep- 
arated from diode rectifier by another NAND 
gate. Increasing oscillatorfrequency gives more 
pulses per second and higher integrated meter 
reading. Each meter range is linear, so value of 
5-pF capacitor can be read on lowest range. 
Diodes are 1N34 or equivalent. R1 is 12K, and 
R2-R6 are 50K trimpots set to values shown in 
table. R7 is 5K, and R8 is 10K trimpot. B1 is 9-V 
transistor battery- Article covers construction 
and calibration with known capacitors. — E. 
Landefeld, Build a Simple Capacitance Meter, 
73 Magazine, Jan. 1978, p 164-165. 



NEGATIVE 
CAPACITANCE 



LC 



EJi 



■* 4 » 



yH? 



■02 
K tOllF 



.01 <«* 



TV- 




CRI ilN9/4 ▼ IN9I4 

1 T T 



_^^>-o* 



T 



CAPACITOR TESTER— Portable instrument 
measures capacitance values to 2500 /tF and 
leakage current with up to 8 V applied. Timer 
U1 operates as clock providing about 350 neg- 
ative-going pulses per second to trigger timer 
U2 and unclamp test capacitor so it charges 
through switch-selected resistor to half of sup- 
ply voltage. U2 then resets, discharging capac- 
itor through pin 7. During charge, pin 3 of U2 is 
high (about 8 V) and duration of high state is 
directly proportional to capacitance. Resulting 
rectangular waveform is applied to unity-gain 
buffer opamp U3 that feeds meter through cal- 
ibrating trimpot R6. Meter deflection is propor- 
tional to average value of rectangular output 



S1 



S2 



3-pole, 3-position, 


A (low-capacitance mode) 


2 section 


B (high-capacitance mode) 




C (leakage mode) 




mode A 


mode B n 


1-pole, 5-position 


HF 


/*F 




A 0.0001 


0.25 




B 0.001 


2.5 




C 0.01 


25.0 




D 0.1 


250.0 




E 1.0 


2500.0 



mode C 



leakage 



S3 



SPST (test) 



waveform and is therefore proportional to ca- 
pacitance. Table gives switch functions. Mode 
B uses larger clock timing capacitor to permit 
measuring larger capacitance values, for total 



of 10 ranges. Article covers construction, cali- 
bration, and use. — P. H. Mathieson, Wide- 
Range Capacitance Meter, Ham Radio, Feb. 
1978, p 51-53. 



CAPACITANCE MEASURING CIRCUITS 



115 



N+15V 



5.1k 



10k 



x- 



1uF 



ii*o- 



100k 
R2 



15 



3329 



■^h 



1uF 



100k 



TT 



DIGITAL 

FREQUENCY 

COUNTER 



IN PERIOD MODE 



C -lOOOpf 



DISPLAY-I.OOOmS 



-15V 



RANGE SWtTCH 




s-r*.C 



n n n rr 



NE535 
(TOP) 



W*. — •— 



I Li LJ l_l U4 



lOt 
CALIBRATE 






ZERO 
ADJUST 



DIGITAL WITH 100:1 RANGE— Frequency 
counter operated in period mode serves as 
readout for Optical Electronics 3329 voltage-to- 
frequency converter. Unknown capacitance is 
connected as external timing capacitance for IC, 
so output period of IC is directly proportional to 
unknown capacitance. To calibrate, connect 
known C and adjust R1 for correct reading on 
digital frequency counter. With values shown, 
1 nF gives period of 1 ms. — "Low Cost Capaci- 
tance Measurement," Optical Electronics, Tuc- 
son, AZ, Application Tip 10262. 



DIRECT-READING FIVE-RANGE— Covers 1 pFto 
1 /tF in five ranges, using easily available com- 
ponents. Trigger source is free-running pulse 
generator using programmable UJT Q1 and in- 
verter-amplifier Q2 to produce narrow -12 V 
output pulse at constant frequency of about 500 
Hz. For trigger pulse, NE555V timer connected 
as mono MVBR initiates output pulse whose 
width increases with value of capacitor under 
test. Meter reads average value of pulse wave- 
form and may be calibrated directly to read ca- 
pacitance. Range resistors should be 5% or bet- 
ter. 10K trimpot in series with meter serves for 
Initial calibration. Zero-adjustment pot Is 
needed only for lower ranges. Use zener-regu- 
lated supply to provide 12 V at up to 50 mA. Full 
type number of Q1 is A7T6028; 2N6027, 2N6028, 
2N6118, and HEP S9001 are similar. Single 
0.0025- /iF capacitor can be substituted for two 
0.005-/xF units in series. — C. Hall, Direct-Read- 
ing Capacitance Meter, Ham Radio, April 1975, 
p 32-35. 



-TLTL 




© © © © 

©T®T© 



E|_JC 



IN4004 

H4— • 




IC power connections 

741 4- 7+ 

7408 7- 1 4+ 

7474 7- 1 4+ 

7492 1 0- 5+ 

7447 8- 1 6+ 

7490 10-1 5+ 



1-99,900 fiF — Circuit converts charging time of 
unknown capacitor to capacitance value shown 
on 3-digit display. S-1 is shown in OFF position, 
with unknown capacitor shorted. When S-1 is 
changed to other position for start of test, C x is 
connected to measuring circuit through range 
switch S-2 and 741 opamp used as comparator. 



60-Hz timing waveform is now applied to sine- 
wave squaring circuit using two sections of 
7408 AND gate. This starts 7490 counters. 
Zener-regulated +9 V is applied to C x through 
selected range resistor. When charging voltage 
of capacitor exceeds reference voltage on in- 



verting input, 741 output goes positive and 
stops counter. Article describes circuit opera- 
tion in detail. Range switch gives scaling factors 
of 1, 10, 100, and 1000.— A. S. Joffe, Now— a 
Digital Capacity Meterl, 73 Magazine, May 
1978, p 58-60. 



116 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Capacitor 
under test 




FIVE RANGES UP TO 1 pF— Direct-reading 
meter gives capacitance values in five ranges, 
all using same 0-100 scale on 100-juA meter. 
Operates from three penlight cells. To calibrate, 
connect known capacitor to jack, close S2, and 
adjust trimmer pot for each range in turn to give 
correct indication of capacitor value on 
meter. — C. Green, Build This Easy Capacitor 
Meter, Modem Electronics, Aug. 1978, p 78-79. 



U>R2L>R4|_»> 




ADAPTER FOR COUNTER— Converts counter 
into digital capacitance meter for measuring 
values down to around 5 pF with better than 1% 
accuracy. Three ranges give full-scale values of 
99,999 pF, 0.99999 #*F, and 9.9999 pF. Positive- 
going count-enable command from frequency 
counter, applied to point A of gate U2A, re- 



moves short-circuit from unknown capacitor C„ 
and enables gate U2C. Capacitor charges ex- 
ponentially through R1 and R2 (range 1) to volt- 
age at which threshold comparator at U1 makes 
flip-flop change state, shorting C x and disabling 
gate U2C. During charge time, 1-MHz pulses are 
applied to counter input. Counter reading then 



TO DECIMAL 

POINT INDICATORS 

IN COUNTER 

(OPTIONAL) 



corresponds to capacitor value. CI is 18 pF, R1 
is 860K, R2 is 100K, R3 is 86K, R4 is 10K, R5 is 
8.6K, R6 is IK, and U2 is 7400 quad NAND 
gate. — R. F. Kramer, Using a Frequency Counter 
as a Capacitance Meter, QST, Aug. 1977, p 19- 
22. 



CAPACITANCE MEASURING CIRCUITS 



117 



MAIN ADJUSTMENT 



CHECKING BY SUBSTITUTION— Uses 1-MHz 
crystal oscillator with fixed-tuned tank circuit 
L1-C2 link-coupled to resonant measuring cir- 
cuit consisting of L4, C4, C5, and unknown ca- 
pacitance. Simple RF voltmeter is connected 
across measuring circuit as resonance indica- 
tor. C4 and C5 have calibrated dials reading di- 
rectly in picofarads. LI is Miller 20A224RBI slug- 
tuned unit adjusted to 250 pH. L4 is Miller 
41A685CBI adjusted to 60 /xH. Links L2 and L3 
are2turns each. To use, close S1, set C5to max- 
imum, and adjust C4 for peak deflection of M1 . 
Connect unknown capacitance to XX with 
shortest possible leads, retune C5 to resonance, 
then subtract this capacitance reading of C5 




from maximum reading to get value of un- 
known capacitor. — R. P. Turner, "FET Circuits," 



0-50 DC 
MICROAMMETER 



Howard W. Sams, Indianapolis, IN, 1977, 2nd 
Ed., p 140-142. 







BOTTOM VIEWS 



D S G 
01 ,02 AND 03 



C1, C4, C5 — 220 i*F. 16 V, Sprague 

227G016CG or equiv. 
C2 — 22 iiF, 16 V, Sprague 226G016AS 

or equiv. 
C3 — 130-pF disk, Sprague 1CC0G131X0100C4 

or equiv: 
D1 — Silicon small-signal diode, 1N914 or 

equiv. 
D2, D3 — Silicon rectifier diode, 200 V, 1 A; 

1N4003 or equiv. 
D4, D7 — Zener diode, 6.2 V, 400 mW, 

1N753 or equiv. 
D5, D6 — Zener diode, 12.0 V, 400 mW, 

R AND C ADAPTER FOR DVM— Self-contained 
circuit provides four ranges of capacitance (0- 
1, 10, 100, and 1000 /uF) and four ranges of re- 
sistance (0-1, 10, 100, and 1000 kilohms) when 
used with QST combination digital voltmeter 
and frequency counter. Auxiliary range posi- 



1N759 or equiv. 
D8 — 3/16-in. red LED, Motorola MLED50 or 

equiv. (11 on pc board). 
F1 — 1/2-A pigtail fuse, Buss MDV 1/2 A, 250 

V. 
J1, J2 — 5-way binding post. (Radio Shack 

package no. 274-661 includes red and black 

posts.) 
Q1, Q2, Q3 — N-channel JFET, 2N5486 or 

equiv. 
S1, S2 — 2-pole, 6-position rotary switch, CTS 

no. T206 or equiv. 

tions on switches are provided for special mea- 
suring requirements such as temperature sen- 
sing, antenna elevation indication, and rain- 
gage measurements. For capacitors, constant- 
current source Q1 charges capacitor linearly. 
When charging voltage makes U1A switch from 



53 — Dpdt momentary toggle switch, Alco no. 
MTA206T or equiv. 

54 — Dpdt toggle switch, Alco no. MTA206P 
or equiv. 

T1 — 12.6-V, 100-mA power transformer, 
Mouser no. 81PG120. Mounting centers 
1-13/16 inch. 

U1 — Dual operational amplifier, National 
Semiconductor type LM1458. Inter- 
changeable with IC type 5558. 

U2 — Linear IC operational amplifier, RCA 
type CA3130. 

positive to negative, C2 stops charging. Voltage 
across C2, proportional to value of unknown C, 
is then fed to DVM. Article covers construction 
and calibration. — R. Shriner, New Tasks for the 
Digital Voltmeter, QST, March 1978, p 19-22. 



118 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




-9V 



BRIDGE FOR 25 pF TO 10 /xF— Uses five refer- 
ence capacitors, one for each range. Linear pot 
VR1 serves for balancing. High-resistance head- 
phones indicate null, and capacitor value is then 
read from setting of VR1 . Scale of VR1 is marked 
for 100 to 10,000 pF for C2 range and 0.01 to 1 
fiF for C4 range. Scale values are multiplied or 
divided for other ranges. Calibration is carried 
out on C2 range, using known capacitor values. 
Tone oscillator can use almost any pair of tran- 
sistors, one NPN and the other PNP. — F. G. 
Rayer, Adrift over Your C's?, 73 Magazine, 
March 1976, p 106-107. 




| + | 10k 4.7k 

D 0-fVW-fW\^-i 

OUTPUT 

Id, TiooiiF 



IOOuA 

FULL-SCALE 

METER 




LINEAR SCALE — Wide frequency range and 
high output current of 555 timer contribute to 
linearity of operation as capacitance meter. 
Timer is connected as astable MVBR with fre- 
quency determined by values used for Ra, Rb, 
and C,. When timer output is high, unknown 
capacitance C x is charged almost to V C c- When 
timer goes low, C x discharges through D,. Use 
100 kHz for 100-pF full-scale reading, 10 kHz for 
1 nF, 1 kHz for 10 nF, and down to 1 Hz for 10 
(iF. Use regulated supply. — R. Horton, 555 
Timer Makes Simple Capacitance Meter, EDN 
Magazine, Nov. 5, 1973, p 81. 




6-DIGIT VALUES— Digital capacitance meter 
provides display of capacitance values from 1 pF 
to 999999 pF (1.0 pF). Start-measurement 
switch drains charge from capacitor under 
measurement and diverts constant-current 
source to ground. Capacitor begins charging. 



and counter accumulates 1-/ts pulses from crys- segment output data for display. Position A of 
tal clock. When capacitor charge voltage SW1 is starting point, B stores data in counter 
reaches threshold of count-inhibit line for display after capacitor measurement, and C in- 
counter, contents of counter are displayed as itiates measurement. Display includes leading- 
capacitance value. Circuit uses Mostek zero suppression. — J. Garrett, What's Your pF?, 
MK50395N six-decade counter that provides 7- 73 Magazine, Dec. 1978, p 234-235. 



CAPACITANCE MEASURING CIRCUITS 



119 



T 



;! 10 K 



ill 

— *- r i — *- r p - 1 — c. 



L 



.-j"-.'"' /1S^ ,-r-.C3 — ^m — ^ 



T H T 



i k D2 ^t 30 



RANGE 


R 


C 




x1 pF 


10k var. 


100 pF 


(CD 


X10pF 




.001 


(C2) 


x100pF 




.01 


<C3> 


x.001 




.1 


(C4) 


x.01 




1 


(C5) 


x.1 




10 


(C6) 



PLL CAPACITANCE METER— Based on fact that 
alternating current floating through capacitor 
depends on applied voltage, frequency, and ca- 
pacitance value. Circuit uses square wave for 
charging capacitor to full voltage, then mea- 
sures current flow as linear function of capaci- 
tance. LM78L15 provides regulated 15 V for 
LM566 PLL VCO. Frequency of VCO depends on 



values of R and C selected by rotary switch S1, 
to give six linear scales: 0-10 pF, 10-100 pF, 
100-1000 pF, 1000 pF to 0.01 pF, 0.01-0.1 /iF, 
and 0.1-1 fiF. Accuracy is about ±5%. Meter is 
100 iiA, Use small signal diodes. — S. Shields, 
How Many pF is That Capacitor, Really?, 73 
Magazine, March 1978, p 48-50. 



InO- 



200p; 



999p 
HI- 



ADJUST <■ 1Qk I!" 



V77? 



ot) 



LOSS ?. ||_ 

NULL <TTT. I" 



-O Out 



10k 

l dot) 



100p 



PERFECT CAPACITOR — Simple circuit shown 
provides equivalent of perfect no-loss 1000-pF 
capacitor at frequencies below about 100 kHz. 
Principle can be used to construct fixed-fre- 
quency capacitance standards for use in high- 
accuracy capacitor bridge. All capacitors are sil- 
ver mica. If mounted in oven, stability can be 1 
PPM and residual phase-angle difference from 
pure capacitance only 1 microradian. — B. J. 
Frost, "No Loss" Capacitor, Wire/ess World, 
Dec. 1977, p 80. 



K5V 



■<5 
680 



47n 470n 4ji7 

j-m- 




+12 V 



R 17 
2k2 



Rl6 



s>^ 




Q+5V 







50 to 100 A 



Switch Positions 1 


Sw, 


START 1 


Sw 2 


REFORM ON/OFF | 


SV» 3 


RANGE I 
M N O P Q 1 
3,000 300 30 3 0'3,u | 



ELECTROLYTICS WITH REFORMING— Auto- 
matic tester for electrolytics applies voltage for 
about 15 s to repolarize dielectric before mea- 
surement is made. This provides sufficient re- 
forming for test purposes, using 12 V through 
1200 ohms, but test should be repeated if leak- 



age current is high because of incomplete re- 
forming. Tone from loudspeaker indicates end 
of 15-s reforming period. Green LED, indicates 
reforming process is ready to start. Red LED 2 in- 
dicates excessive current is flowing during re- 
forming. LED 3 flashes to indicate test capacitor 



is being charged during measuring cycle. Article 
covers construction and calibration in detail. IC, 
is SN74123N, IC 3 is SN74121N. and IC, is 
SN7413N. — A. Drummond-Murray, Electrolytic 
Capacitor Tester, Wireless World, May 1977, p 
47-49. 



120 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




RESISTOR 


SCALE 


R2 - IO0K 


X 100 pF 


R3 -IOK 


X 1000 pF 


R* -IK 


X .01 (IF 


RS - IOOa 


X .IpF 



ALL RESISTORS- 1/2 W, 5% or Dttttr 

0.0001 TO 1 nF IN FOUR RANGES— Simple 
bridge uses AF voltage from Cordover CPO-4 
code practice oscillator module, fed through 
transistor output transformer connected in re- 
verse for impedance matching. Earphones 
serve as null detector, but amplifier can be 
added for greater sensitivity or CRO used. Only 
one scale need be calibrated, using known val- 
ues of capacitors. — W. P. Turner, Build a Basic 
Bridge, 73 Magazine, Nov. 1974, p 95. 








C BY GRID DIP — Values of unknown capaci- 
tances up to about 1000 pF can be measured 
with simple circuit used with grid-dip oscillator. 
Coil L can be 6 turns of stiff wire. To calibrate, 
close variable capacitors C1 and C2 fully, tune 
for dip, and note dip frequency at pointer posi- 
tion of C2. Now connect known capacitors up 
to 1000 pF one by one to CX, retune C2 for dip, 
and mark capacitor value on C2 dial. Close C2, 
then repeat calibration for C1 while using 
smaller capacitors up to 50 pF. — F. G. Rayer, 
GDO to Find C, 73 Magazine, Aug. 1974, p 35. 



■6.2MEG 








-D, 








* 




r 


• • 



TEST 
I SPEAKER CLIPS 



ill 



0.5-pF TO 0.001-juF COMPARATOR— Provides 
audio-tone comparison of built-in reference ca- 
pacitor to unknown capacitor connected be- 
tween test clips. Frequency of tone is about 8 
kHz for 0.5 pF, dropping to 100 Hz as capacitor 
value goes up to 0.001 juF. Larger capacitor val- 
ues merely turn LED on and off; 0.1 juF gives 
flashing at about 5 Hz. Any NPN audio or switch- 
ing transistor can be used in place of MPS6512. 
Suggested reference values for capacitor bank 
are 0.7, 3, 5, 10, 25, 50, 100, 330, 470, 680, and 
820 pF.— W. Pinner, The Capacitor Comparator, 
73 Magazine, March 1977, p 49. 



COMPUTERIZED METER— With 4.7 megohms 
for R, simple 555 timer circuit used in conjunc- 
tion with computer measures capacitors in five 
ranges from below 100 pF to 0.1 pF. For larger 
range, resistor value can be changed. Article in- 
cludes BASIC software suitable for 8080-based 
systems, including calibration program based 
on known values of capacitance. 555 mono 
MVBR is triggered under control of computer 
output port bit, with count being made while 
mono is timing out. Count is averaged over ten 
triggerings, then multiplied in computer by cal- 
ibration factor to give capacitance value. Any 
desired type of output indicator can be used. — 
J. Eccleston, Computerized Capacity Meter, 73 
Magazine, July 1978, p 88-89. 



FROM PORT OUT » 



TO PORT IN 





























A 


I. 


7 


R 






2 


TRIGGER 

555 










6 

— 








3 


OUTPUT 




5 




o 

'T 












^0 OI^F 



























CAPACITANCE MEASURING CIRCUITS 



121 



OPTIONAL BATTERY CONNECTION (EXTERNAL POWER) 

y di 

+ >T— W-l 
9V 




CALIBRATE _< 



ji 

■^ UNKNOWN 
CAPACITOR 



O— I ,, <*<_ 

°~-"-AAA/ » T + l mA J~1 

, .OK ^J A-, 



556 
TOP VIEW 



EXCEPT AS INDICATED, OECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS ( JlF I ; 
OTHERS ARE IN PICOFARADS I pF OR J1J>F); 
RESISTANCES ARE IN OHMS ; 
k-IOOO, M-IOOO OOO. 



/-T7J+ 



J3 

<T0 
VOM 



DUAL TIMER MEASURES C— One section of U1 
(two 555s in single package) is connected as 
oscillator that serves as trigger for other section 
(U1B). Ratio of R1 and R2 determines length of 
pulse generated during each oscillation cycle, 
while CI and same resistors set frequency at 
about 500 Hz. U1B produces predetermined -du- 
ration output pulse for each start pulse regard- 
less of starting pulse length. Pulse duration is 
set by R4-R7 and external capacitor being mea- 
sured. Smaller capacitor in given range pro- 
duces shorter output pulse from U1B mono 
MVBR. Average pulse power increases with 
pulse length and increases meter reading lin- 
early so capacitance value is indicated directly. 
Values shown give ranges of 1000 pF, 0.01 fiF, 
0.1 iif. and 1 fiF full-scale. R10 serves as cali- 
bration resistor for all three higher scales. D1 is 
50-PIV or higher silicon power-type diode, and 
D2 is 1N914 or equivalent. — D. A. Blakeslee, An 
Inexpensive Capacitance Meter, QST, Sept. 
1978, p 11-14 and 37. 



RANGE SWITCH POSITION 
lOOpF tOOOpF .OIjiF O.ljiF I.OpF 



6 VOLT 
BATTERY PACK 



• R3 < R4 > PS 2R6 

' 4.7M > 470k > 47k > 4.7k 



TEST -L- 

TERMINALS ^J^ 

Q ■> 






- I mA (mA 



FIVE RANGES TO 1 *iF WITH TIMERS— Based 
on fact that output pulse width of 555 timer var- 
ies linearly with value of timing capacitance 
used. If timer is triggered with constant fre- 
quency, average DC value of resulting pulse 




lib 



ZERO ADJUST 



train is linear function of pulse width. DC meter 
then reads capacitance values linearly. Decade 
capacitance ranges are obtained by switching 
value of timing resistor. Trimpot for each range 



is adjusted for zero meter reading when push- 
button is pressed, without test capacitor. — C. 
Hall, Simplified Capacitance Meter, Ham Radio, 
Nov. 1978, p 78-79. 



CHAPTER 11 

Cathode-Ray Circuits 



Includes probe circuits, preamps, deflection amplifiers, 2-channel and 4- 
channel trace multipliers, triggered sweep, dynamic focus correction, B-H and 
Lissajous pattern generators, time-mark generator, and TV typewriter circuits. 
See also Game, Power Supply, Sweep, and Television chapters. 



25V 



+ 200V 




Y AMPLIFIER FOR CRO— Combines advantages 
of differential output stage and high-impedance 
JFET input stage. Silicon input diodes provide 
crude overload protection for input, while Tr 2 
acts with Tr, for level-shifting as well as ampli- 
fying. R, is used to set quiescent output voltage 
of Tr 2 at about 15 V; this setting is critical, and 
may require multiturn pot. Article gives setup 
procedures. — G. A. Johnston, Deflection Am- 
plifier for Oscilloscopes, Wireless World, April 
1975, p 175. 



CURRENT AMPLIFIER— Used in FET curve 
tracer to amplify drain current passing through 
R 14 sufficiently to give required Y output for os- 
cilloscope. Uses SN72741P opamp as difference 
amplifier. Article gives other circuits of curve 
tracer and calibration procedure. — L. G. Cuth- 
bert. An F.E.T. Curve Tracer, Wireless World, 
April 1974, p 101-103. 



set current 
Q 




INPUT Q- 




BANGE 
X 10 
X 100 



FREQUENCY 
D.C. 100 KHZ 
D.C. 10 KHZ 



Output Voltage P.P. 
D.C. 28V 

10 KHZ 27V 

100 KHZ 3V 



SCOPE PREAMP— Extends vertical sensitivity 
range of scope or VOM at minimum cost. Volt- 
age at output is in phase with input. Switch 
across C gives choice of AC or DC operation. 
Table gives frequency and output voltage lim- 
its. Input impedance is about 500 kilohms. — G. 
Coers, High-Gain AC/DC Oscilloscope Amplifier, 
EDNIEEE Magazine, Feb. 1, 1972, p 56. 



122 



CATHODE-RAY CIRCUITS 



123 



h20VO 




+ 20OV 



+12VtO +18V 



O+20V 



overall gain set by 
these resistors 



to 

oscilloscope 
horiz. 



to 

Schmitt 
trigger 



2N4S94, 
2 N 4851 



^ 



r-@ 



TJ T\T T 



switch position and 
capacitor values as needed 



TRACE QUADRUPLER— Designed for use with 
DC oscilloscopes. Constant-current UJT oscil- 
lator produces linear sawtooth for triggering 
Schmitt trigger and serving as horizontal sweep 
voltage. Frequency is varied by switching ca- 
pacitors, and can be up to about 100 kHz. Emit- 
ter-follower may have to be added to UJT out- 
put to prevent loading of timing capacitors by 
low impedance of Schmitt trigger. Used to 
quadruple maximum time-base frequency of 
oscilloscope. — J. A. Titus, Trace Quadruples 
Wire/ess World, Oct. 1972, p 479. 



O-15V 



Y AMPLIFIER WITH 10-MHz BANDWIDTH— Rise 
time is 40 ns. Tr,-Tr 4 form constant-current tail, 
with Tr 5 improving linearity. Tr 6 and Tr 7 are com- 
plementary emitter-followers, as also are Tr 8 
and Tr 9 , for feeding deflection plates. Input 



should be from 50-ohm source to achieve full 
bandwidth. Other complementary small-signal 
transistors rated above 200 V can be used. — B. 
J. Frost, Wideband Y Amplifier for Oscilloscope, 
Wireless World, June 1976, p 71. 



DYNAMIC FOCUS CORRECTION— Provides 
sum of squares of vertical and horizontal posi- 
tion voltages, as required for focus correction in 
high-resolution flat-face magnetically deflected 
CRT. Circuit uses Optical Electronics 5898 four- 
quadrant analog multipliers to give required 
squared outputs, along with 9831 opamp hav- 
ing comparable bandwidth. Input summing re- 
sistors for horizontal and vertical deflection am- 
plifiers are chosen for compatibility with 
amplifiers being used. Select current-sampling 
resistors to generate 10-V peak signal. — "Dy- 
namic Focus Correction with Analog Function 
Modules," Optical Electronics, Tucson, AZ, Ap- 
plication Tip 10127. 



Vertical 

Ramp 



Horizontal 
Ramp 




Vertical Yoke 



Vertical Yoke 
Current Sampling 
Resi stor 




9831^ 

V 2 + H 2 
Dynamic Focus 
^^ Correction 
^- Signal 



i Horizontal Yoke 
Current Sampling 
Res is tor 



124 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



CONTRAST 
5k 



Ik. 



X 

J 



-O 200V 



50 yf 



30V 



O [ 2N3742 



500 pHy CRT, 

s vvv ▼ ARC 

iMnai a GAP 



2N4091 



X 



H L__, 



BRIGHTNESS 



3L 



E±I 




50 uF 



I 



I 



CATHODE DRIVE FOR CRT— Cascode connec- 
tion of 2N4091 JFET and 2N3742 bipolar tran- 
sistor provide full video output for cathode. 
Gain is about 90. M-derived filter using stray ca- 
pacitances and variable inductor blocks 4.5- 
MHz sound frequency from video amplifier. Cas- 



code configuration eliminates Miller capaci- 
tance problems of JFET, allowing direct drive 
from video detector. — "FET Databook," Na- 
tional Semiconductor, Santa Clara, CA, 1977, p 
6-26-6-36. 




OUT 



±7 VDC OFFSET— High-impedance current 
source Q, provides desired level shift for AC sig- 
nals in video circuit whose DC level controls in- 
tensity of CRT. Input and offset signals are fed 
to base of Q 3 which drives complementary-sym- 
metry emitter-follower Q,-Q 2 . For values 
shown, level can be shifted about ±7 VDC. — P. 
B. Uhlenhopp, Variable DC Offset Using a Cur- 
rent Source, EDN IEEE Magazine, Aug. 15, 1971, 
p46. 



r > T^ 



1/6 74C04 i . 
14 






CHOP 


ALTERNATE 


R 


20KS! 


120K :i 


C 


0.00056 pF 


0.022 (i F 


F 


50 kHz 


200 Hz 



+5 V 

Q 



14MM74C73 



J Q 

CLOCK 
K CLR Q 



V4MM74C73 



J Q 

CLOCK 

K CLR° 



r 



CM 



0~ J 



CM 
CM 



•"CH^_r 



r iI CH^-S" 



* ,J " urtr\ 

J22 Li 



u-q_^ r 



i= i»-r 



Li 



7 



T 



-OS, 



TO 
SCOPE 



-OS 2 



-OS 3 



-Os 4 



<§> 



-15V " 1 

FOUR-CHANNEL ADAPTER FOR CRO— DG201 used in chop mode for signals below 500 Hz. "=" 

CMOS analog switch controlled by 50-kHz clock Frequencies above 500 Hz are best viewed in of CRO.— "Analog Switches and Their Applica- 

allows display of four input signals slmultane- alternate mode with clock frequency of 200 Hz. tions," Siliconix, Santa Clara, CA, 1976, p 7-63- 

ously on single-trace oscilloscope. Adapter is One of inputs is used to trigger horizontal trace 7-66. 



CATHODE. RAY CIRCUITS 



125 



■ +200V 



4 c.r.t. plates < 

22k< <22k 

2W < /^__\ S2W 



+ 26V 



input 




+ 28V 



ELECTROSTATIC-DEFLECTION AMPLIFIER— 
Combines frequency response of cascode am- 
plifier with linearity of long-tailed pair fed by 
constant current. Adjust R for 3 mA through 
each load resistor. Output transistors require 
small heatsinks. — G. A. Johnston, Deflection 
Amplifier, Wireless World, Nov. 1973, p 560. 



TO MEMORY ADDRESS BUS 



FROM ONE PULSE 
PER CHARACTER 
LOGIC 



innr 



WINKING CURSOR 
TO VIDEO 
COMBINER 

JL 

BLINKER SOURCE 
7.5 Hz 



READ PULSE 
■o TO SCREEN READ 




♦ 5V 
GND 
VSYNC 



CMOS LOGIC »5-V, 
-5-V SUPPLY INPUT 
AND WRITE SIGNALS 
4r . *5-V SWINGS 

♦ ■OPTIONAL LOGIC 
TRANSLATORS- 
NOT NEEDED IN 
SOME SYSTEMS 



access, and writing during vertical interval for 

displaying 512 characters per page on TV 
CURSOR FOR TV TYPEWRITER — Complete screen. External 7.5-Hz source is required to screen. — D. Lancaster, "TV Typewriter Cook- 
CMOS logic cursor and update system is shown make underline cursor flash to indicate position book," Howard W. Sams, Indianapolis, IN, 1976, 
for system using RAM memory, direct memory at which next character will be entered on p 128-129. 



126 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




OPTOISOLATOR FOR PROBE— Offsets need for 
potentially dangerous practice of floating oscil- 
loscope with respect to ground. Also permits 
simultaneous display of two voltages with cor- 
rect polarity on double-beam oscilloscope 
when one of them is floating. Texas Instru- 
ments TIM 12 optocoupler used has bandwidth 
of about 30 kHz. Three ranges give choice of 1 : 1 , 
10:1, and 100:1 input attenuation. Set RV 2 to 
bias phototransistor of optocoupler to center of 
its linear range (about 4.5 V between pins 4 and 
5), then set RV, to give unity input/output ratio 
on range 1. RV 3 is set to give zero DC output 
when input terminals are shorted, but can be 
omitted if zeroing of output level is unneces- 
sary.— A. F. Sargent, Simple C.R.O. Input Isolat- 
ing Probe, Wireless World, Feb. 1976, p 76. 



VIDEO 
INPUT 




1N914 OR 1N4148 
* * 

H H ■ 



H(- 



TVT A * 



0.1 uF 



T" r 



r 



:5pf 



250 uH 
• PEAKING 



•4.3K 



VIDEO 
DETECTOR 



VIDEO 
DRIVER 



*-NEW 
COMPONENTS 



3V 
BIAS SOURCE 



TV INTERFACE FOR TYPEWRITER— Video input 
circu it forblack and white transistor TV receiver 
permits feeding video output of TV typewriter 
to video driver in set, for producing character or 
game display on TV screen. Use of direct cou- 
pling eliminates shading effect or changes in 
background level as characters are added. 
Diodes provide 1.2-V offset in positive direction 
so in absence of video the video driver is biased 
to blacker-than-black sync level of 1.2 V. With 
white video input of 2 V, driver is biased to usual 
3.2 V of white level. Hot-chassis TV sets can 
present shock hazard. — D. Lancaster, "TVType- 
writer Cookbook," Howard W. Sams, Indian- 
apolis, IN, 1976, p 190. 



A 3-30 pF 




COLOR 
SELECT 
INPUTS 

I MUST RETURN TO 000 
REFERENCE PHASE DURING 
AND AFTER H SYNC PULSE) 



4512 (CMOS I ' 
0NE-0F-EIGHT 

SELECTOR 
330 



USE SUPPLY VOLTAGE 

VARIATION ON 4050 

TO TRIM COLORS 



680 pF i 



1 



H 



2.5K 



0.01 uF 



SET TO 25% OF 
'PEAK- WHITE LEVEL 



VIDEO 
-*- COMBINER 
(100OL0ADI 



COLOR FOR TV TYPEWRITER— Uses 3.579545- 
MHz crystal oscillator to drive string of CMOS 
buffers forming digital delay line. Output delays 
caused by propagation times in each buffer can 
be used directly or can be trimmed to specific 
colors by varying supply voltage. Reference 



phase and delayed color outputs go to 1-of-8 
data selector whose output is determined by 
code presented digitally to its three color select 
lines. Selector drive logic must return to 000 
(reference phase) immediately before, during, 
and for at least several microseconds after each 



horizontal sync pulse so set can lock and hold 
on reference color burst. Sine-wave output 
chrominance signal is cut down to about one- 
fourth of maximum video white level. — D. Lan- 
caster, "TV Typewriter Cookbook," Howard W. 
Sams, Indianapolis, IN, 1976, p 205-206. 



CATHODE-RAY CIRCUITS 



127 



47k 47k 

,MC1458CPI 50|>FaC'0" F 

■I . ZV V 



AREA J 10k \? ^^ . VERTICAL 

o (^^^t 5k -L 

OSCILLATOR <// V\V — -- ■ ■ 

input Av^J/V - 4 8 / / 



7 HORIZONTAL 




f~K 



FROM AF 
GENERATOR 
OR 
MODULATOR 




B-H LOOP DISPLAY— Low-cost dual opamp cir- 
cuit allows display of hysteresis loop on cali- 
brated XY oscilloscope. Two windings are 
placed on core to be tested, with opamp of flux- 
measuring system connected to secondary for 



deriving vertical deflection input representing 
flux B. Article gives design equations and de- 
tails of circuit operation and use. — D. A. Zinder, 
X-Y Oscilloscope Displays Hysteresis Loop of 
Any Core, EDN Magazine, Feb. 5, 1975, p 54-55. 



.022 



ELLIPTICAL PATTERN— Connection shown 
gives Lissajous-type elliptical pattern on CRO 
from ordinary AF signal generator. Modulation 
can be added to either vertical or horizontal feed 
for CRO— Novice Q & A, 73 Magazine, March 
1977, p 187. 



v+ 




Clock input 



TIME-MARK GENERATOR— Produces precisely 
spaced output pulses suitable for calibrating 
CRO time bases. Can be programmed in binary 
by using 2240 for A, or in BCD by using 2250. 
Use crystal oscillator or other high-accuracy 
source for external clock. Time interval of out- 
put pulse is equal to clock width multiplied by 



{T>o O 

"^ Output 

tCMOS Inverters 

n + 1, where n is number programmed into A, 
(1 to 255 for 2240 and 1 to 99 for 2250). Circuit 
can be programmed electronically by micropro- 
cessor if desired.— W. G. Jung, "IC Timer Cook- 
book," Howard W. Sams, Indianapolis, IN, 1977, 
p 218-220. 




y&— o s 



HIGH-Z PROBE— Provides about 1200-megohm 
input impedance to CRO, with unity gain. Pot 
adjusts equalization at higher frequencies. Q1 
can be U112, 2N2607, 2N4360, orTIM12. Q2 can 
be 2N706, 2N708, 2N2926, 2N3394, or HEP 50.— 
Circuits, 73 Magazine, March 1974, p 89. 



♦ 9V (FROM OSCILLOSCOPE 
A POWER SUPPLY) 



FROM VERTICAL 
AMPLIFIER 




*C0NNECT TO GROUND IF SCOPE 
DOES NOT HAVE -9V AVAILABLE 



TRIGGERED SWEEP— Developed for use with 
general-purpose CRO in troubleshooting digital 
circuits, to provide one horizontal sweep of 
cathode-ray beam each time circuit is triggered 
by input signal pulse. Noninverting input of 741 
opamp is connected to vertical amplifier of CRO, 



-9V 
(FROM OSCILLOSCOPE 
POWER SUPPLY) 



and inverting input is used to control trigger 
level. When input signal rises above trigger 
level, output of opamp swings to -V and makes 
output of 556 timer go high, allowing output 
capacitor to charge at constant current through 



lO^F 



transistor in series with resistor. Result is nearly 
perfect ramp voltage. All diodes are 1N914. Q1 
is any PNP switching transistor.— W. J. Prud- 
homme. Trigger Your Oscilloscope, Kilobaud, 
Aug. 1977, p 34-38. 



128 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




ELECTROSTATIC-DEFLECTION AMPLIFIER— 
Circuit develops equal-amplitude but opposite- 
polarity sawtooth outputs when sawtooth 
input is applied to gates of Q1 and Q2. Q1 is con- 
nected as common-source amplifier for apply- 
ing opposite-polarity sawtooth to gate of Q3. 
Polarity at output of Q3 then becomes same as 
that of input, increased to amplitude suitable 
for deflection plates of CRT. Sawtooth at output 
of 02 has opposite polarity. Circuit values are 
chosen to balance gain so both outputs have 
same magnitude. — E. M. Noll, "FET Principles, 
Experiments, and Projects," Howard W. Sams, 
Indianapolis, IN, 2nd Ed., 1975, p 229-230. 



DEFLECTION-PLATE AMPLIFIER— Resistive col- 
lector network of symmetrical differential am- 
plifier is replaced by constant-current source to 
improve slew rate of deflection amplifier driving 
capacitive load such as deflection plates of elec- 
trostatic cathode-ray tube. Q, and Q 2 are iden- 
tical current sources. Network Q,-CR,-Q7-R6-Rs 
forms current source for Q,. Q 7 is used as 6.2-V 
zenerdiode. — W.Peterson, Current Sources Im- 
prove Amplifier Slew Rate, EEE Magazine, Nov. 
1970, p 102. 



Re 

100 k 

1W,5% 



CRI 
IN9I4 



Rt 
100 



®.o. 
2H 



oTC) 



0.5-8 pF 



2N406S 

Ra 

330 

1% 



03 
2N4063 



R|3 
100 

<> 



.R« 
330 



R, 02 
M \ 100 k 2N4063 

10k 
Ik /5* 



TO CRT AXIS 
-* DEFLECTION PLATES *" 



RlC 
47 



Rll 
47 



100k 



CR2 

IN9I4 



€> 



"12 l y 

K)0k 5 fc 2 



04 
2N4063 



(U ' **(% 

! 2 Vi/ (212N326I \jS/ 



* R » 
390 

IW,5% 



Qe 
2N3638A 



0.5-8pF 



R5 
lk,l% 



R4 
lk,l% 



VOLTAGE RANGE 



VERTICAL 
INPUT 



®- 



m 



AC ^ DC r- 

^n / 

«-i — U — i-o / »o 



y- 



3-12 
pF 



£^X^ 



cw lew 



5-25 pF 






27 pF 



qao- 




TO VERTICAL 
" AMPLIFIER 



TO VERTICAL 
"AMPLIFIER 



DIFFERENTIAL VERTICAL AMPLIFIER — Uses each connected in single-gate configuration. large signals without overloading. — "Linear In- 
two RCA 40841 dual-gate FETs in vertical input Circuit is designed for frequencies up to 500 tegrated Circuits and MOS/FET's," RCA Solid 
stage of solid-state oscilloscope, with gates of MHz. Wide dynamic range permits handling of State Division, Somerville, NJ, 1977, p 435-436. 



CATHODE-HAY CIRCUITS 



129 




I 



1« 



.4T,iF 



HIGH-Z CRO PREAMP— Darlington circuit pro- 
vides extremely high input impedance (over 2.2 
megohms). With input shorted, noise level is 78 
dB down as read at output with VTVM. Linearity 
is within 1.5% for inputs from 100 /iV to 1 mV, 
and frequency response is ±2 dB from 100 Hz to 



350 kHz. Originally designed to boost input to 
CRO, but can be adapted to many other appli- 
cations requiring high gain, low noise, and high 
input impedance. — J. Fisk, Circuits and Tech- 
niques, Ham Radio, June 1976, p 48-52. 




SIGNAL SWITCHER— Two-tube electronic 
switch serves in effect to provide simultaneous 
presentation of two different signals on CRO 
screen by switching signals alternately Id ver- 
tical input at rate fast enough so both displays 
are seen. — Novice Q & A, 73 Magazine, March 
1977, p 187. 



AA; 




uwrzii ~wr 



-w- 



TRIGGERED SWEEP FOR CRO— Combination of 
555 timer and standard opamp minimizes cost 
of adding triggered sweep to oscilloscope not 
having this feature. Timer is triggered by apply- 
ing vertical-amplifier signal through opamp, in- 
itiating charging of sweep capacitor C. When 
capacitor voltage reaches control voltage of 
timer (0.33 V cc ), flip-flop in timer resets and ca- 



SIGNETICS NE55S 



COMPARATOR 



DISCHARGE 



COMPARATOR 



| V REF 



T 




*VCC 3 

,ook Ay 



0kH(- OR 



C ' ± 'S"' ±0 1 F 



pacitor discharges to form retrace of sweep. — 
"Signetics Analog Data Manual," Signetics, 
Sunnyvale, CA, 1977, p 726. 



CHAPTER 12 

Clock Signal Circuits 



Covers circuits for generating clock pulses at frequencies ranging from 1 Hz to 
well above 30 MHz for use in digital circuits of multiplexers, memories, 
counters, shift registers, microprocessors, videotape recorders, and digital 
cassette recorders. 



DC O 

FROM 

MAIN POWER 
SOURCE 



D, 



1N4001,. 
.0, 



BACKUP . 
POWER 



I 

i 




0.01 nF «T» 



-vw- 



6.3V RMS 
(60 Hz) 






— O+sv 
TO SYSTEM 



-O60H* 
OUTPUT 



, C 2 

' 0.01 iiF 



60-Hz CLOCK OUTPUT FROM 555— Basic 555 
timer IC produces constant 60-Hz rectangular 
output for use as noninterruptible free-wheel- 
ing clock source. C, introduces filtered 60-Hz 
power-line reference component across C, at 2 
V P-P. This signal overrides normal timing ramp 
of 555, causing it to act as amplifier or Schmitt 
trigger. When AC line power fails, C, resumes 
normal function as timing capacitor for 60-Hz 
astable MVBR. Circuit can easily be adjusted for 
other reference frequencies. — W. G. Jung, Take 
a Fresh Look at New IC Timer Applications, EDN 
Magazine, March 20, 1977, p 127-135. 



C,»C,, CHOSE R, FOR 

> 1/3 V+ P-P VOLTS ACROSS C, 




CLOCK 
A 
B 
C 




FOUR-PULSE BURST— Generates burst of four 
clock pulses each time switch is pressed. Mod- 



ifications can produce any desired number of 
pulses in burst. Reliability of pulse count is en- 



sured by use of debouncing latch using pair of 
7400 gates. VCC is +5 V.— E. E. Hrivnak, House 
Cleaning the Logical Way, 73 Magazine, Aug. 
1974, p 85-90. 



130 



CLOCK SIGNAL CIRCUITS 



131 




"cc 2 CLOCK 0.685(R A + R B )C = 15jisec 

9 GENERATOR 0.685(R„)C = 5 M sec 

1/2 7473 



(1/4 7402) 



-Q_Jd-j-c C p 



7rZ C, = lOOOpF 

LL _L R b ■= 7.3k 
~ ~ R. = 14.7k 



TWO-PHASE CLOCK TO 1 MHz— Signetics 555 
timer is used es oscillator to generate nonover- 
lapping clock pulses as required for most two- 
phase dynamic MOS memories and shift regis- 
ters. Duty cycle is determined by values of ex- 
ternal resistors R, and R B which, together with 
timing capacitor C, determine frequency of os- 



1/4 7402 



♦ 1 



::£>-< 



1/4 7402 



dilation. 7473 flip-flop controls phase that is 
switched on through 7402 NOR gates. Article 
gives timing waveforms and equations. Maxi- 
mum operating frequency is 1 MHz. — G. Schlitt, 
Monolithic Timer Generates 2-Phase Clock 
Pulses, EDN Magazine, Aug. 1, 1972, p 57. 




f s 5.1li|Cl 



SQUARE-WAVE CLOCK— One section of Harris 
HA-4900/4905 precision quad comparator gives 
excellent frequency stability as self-starting 
fixed-frequency square-wave generator for 
clock applications. R, and C, determine fre- 
quency, and R 2 provides regenerative feedback. 
For higher precision at frequencies up to 100 
kHz, crystal may be used in place of C,. — "Linear 
& Data Acquisition Products," Harris Semicon- 
ductor, Melbourne, FL, Vol. 1, 1977, p 2-96. 



1/6 MC7404 % MC3001 




CLOCK WITH REFRESH CONTROLS— Crystal- 
stabilized 1-MHz clock source such as Motorola 
K1100A produces complementary 5-V clock 
outputs required for phases 1 and 2 of MC6800 
MPU and also provides interface signals re- 
quired for dynamic (refresh request and refresh 
grant) and slow (memory ready) memories. Re- 
fresh control circuit uses MC7479 dual latch, 
MC7404 hex inverter, and pair of 10K pull-up re- 
sistors. If refresh request state is low when sam- 



pled during leading edge of phase 1, phase 1 is 
held high and phase 2 low for at least one full 
clock cycle. Refresh grant signal is high to in- 
dicate to dynamic memory system that refresh 
cycle exists. If memory ready line is low when 
sampled on leading edge of phase 2, phase 1 is 



BUS 02 



held low and phase 2 high until memory ready 
line is brought high by slow memory controller. 
All transistors are MPQ6842. — "Microprocessor 
Applications Manual" (Motorola Series in Solid- 
State Electronics), McGraw-Hill, New York, NY, 
1975, p 4-57-4-58. 



132 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



SINE = WAVE INPUT 



800 mV p-p 



0.01 «F 



T 



<100 
1 R « 



100 



MC10131 



^L.0.01 



R =R,-220 




510 



CENTERING CLOCK SIGNAL— Circuit gener- 
ates DC bias across complementary outputs of 
Motorola MC10131 flip-flop for optimum oper- 
ation with emitter-coupled logic (10,000 series). 
Bias is independent of state of flip-flop, which 
uses toggle frequency of about 150 MHz. Article 
covers applications for other flip-flops and 
counters requiring maintenance of best toggle 
frequency over wide temperature range. — T. 
Balph and H. Gnauden, Build a Clock Bias Circuit 
for ECL Flip-Flops, EDN Magazine, May 5, 1976, 
p116. 



GLITCH CORRECTOR — Circuit shown prevents 
TTL devices from seeing two clock pulses when 
output of 555 timer has glitch on falling edge at 
about 0.8 V. — J. Magee, Glitch, 73 Magazine, 
Jan. 1976, p 10. 



I8K >\K 




~C 



►CLOCK OUT 






4k7 
BC109 i w\ * 



I » 

777T 




47 >4k7 



POWER SUPPLY 



>6V 




-5WV 



^ /<7\ 100 




_ 4-V3 
4-OOmW 



* 




6(i8 


100ms - 10ms 


680 n 


10ms - 1ms 


68n 


1ms- 100 fis 


6.800P 


lOOps - 10 ^s 


680 p 


10|i.s-*1tis 


30p 


1|iS- 100ns 



VARIABLE WIDTH AND PRF— Low-cost pulse 
generator uses versatile dual monostable IC to 
provide clock pulses that can be varied in width 
over wide range by changing sizes of two ex- 
ternal capacitors and adjusting 47K linear pots. 



Switched bank of six capacitors can be used in- 
stead, to give on or off times ranging between 
1 00 ms and 1 00 ns, as given in table. With switch 
in external position, on-time mono is driven by 
three transistors connected as Sen mitt trigger 



+ 5V 



giving pulse having same frequency as that of 
input signal. VR, sets trigger level. Suitable reg- 
ulated 5-V supply circuit is also shown. — J. Gar- 
rett, Pulse Generator, Wireless World, Feb. 
1976, p 78. 



CLOCK SIGNAL CIRCUITS 



133 



1 (if Cer 




ADJUSTABLE CLOCK WITH MEMORY READY— 
Additional timing resistor is switched in or out 
of MC8602 pulse-width generator for phase-2 
clock to provide memory-ready feature along 
with variable clock frequency for MC6800 mi- 
croprocessor. Selection of timing resistors for 
phase 1 and phase 2 permits generation of all 
combinations of phase 1, phase 2, and stretched 
phase 2 pulse widths. All transistors are 
MPQ6842. — "Microprocessor Applications 
Manual" (Motorola Series in Solid-State Elec- 
tronics), McGraw-Hill, New York, NY, 1975, p 4- 
61. 



VtP 



5e> 



L>c 



> 



EDGE DETECTOR— Half of 9014 quad EXCLU- 
SIVE-OR gate serves for generating output 
pulse for both low-to-high and high-to-low tran- 
sitions of input signal. Used for regenerating 
clock in self-clocking pulse-width modulation 
transmission system. Circuit acts as frequency 
doublerfor square-wave input. With 1000 pF for 
C, output pulse width is 70 ns; for 200 pF, width 
is 30 ns; and when C is 0, width is 10 ns. — Cir- 
cuits, 73 Magazine, Aug. 1974, p 99. 



1.0O0P 



'WW— O + 7-2V 



■f—VWV — oov 
68 




■Q-7-2V 



320 kHz FOR CALCULATOR— Two low-cost TTL V and -7.2 V. NAND gates of ICs are connected available as soon as supply voltage is applied.— 
ICs generate 320-kHz clock signals for electronic to form free-running multivibrator, with self- T. J. Terrell, Clock Generator for Electronic Cal- 
desk calculator. Output swings between +7.2 starting gate C ensuring that clock waveform is culators. Wireless World, Dec. 1975, p 575. 



134 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



1-Hz CLOCK WITH BATTERY BACKUP— Circuit 
normally produces output pulses at 1-s inter- 
vals with basic accuracy corresponding to that 
of power-line frequency. Programmable 8260 
timer operates as divide-by-60 counter produc- 
ing output swing compatible with TTL or 5-V 
CMOS loads. With backup power applied to QR 
gate D,^, circuit operates reliably at 1 s over 
supply range of 5-15 V. Power drain is mini- 
mized at ±5 V.— W. G. Jung, "IC Timer Cook- 
book," Howard W. Sams, Indianapolis, IN, 1977, 
p 214-215. 



Primary DC 



Backup DC o 




o Output (1 pulse/second) 



+5VO- 




30 pF 30 pF 



-60 



-± F 
Iff 



OUTPUTS 

"IT 

O 1 PULSE/SEC 



-Ol PULSE/MIN 



WATCH-CRYSTAL TIMER— When used with 
standard 4.194-MHz watch crystal, Intersil 7213 
crystal-controlled timer generates outputs of 1 
pulse per second and 1 pulse per minute, using 
internal divider chain. CMOS dynamic and static 
dividers keep power dissipation under 1 mW 
with 5-V supply.— B. O'Neil, IC Timers— the 
"Old Reliable" 555 Has Company, EDN Maga- 
zine, Sept. 5, 1977, p 89-93. 



.iMf Csramic 



too 



1 MHz 50 1 2% Duty Cycle 



V. MC30O0 V. MC3000 '/. MC3001 

(74H00) (74H08) 



x> 



CLOCK FOR MC6800 — Produces nonoverlap- 
ping complementary 5-V clock outputs as re- 
quired for phase 1 and phase 2 clock inputs of 
microprocessor. Oscillator can be any source 
having maximum frequency of 1 MHz with TTL 
levels and 50% duty cycle, such as Motorola 
K1100A. MC3OO0 and MC3001 TTL gates are 
chosen for their speed and drive characteristics. 
All transistors are MPQ6842. — "Microprocessor 
Applications Manual" (Motorola Series in Solid- 
State Electronics), McGraw-Hill, New York, NY, 
1975, p 4-1-4-6. 



54 MC3000 54 MC3001 




MPU 01 



I MPU 02 and 

™ DBE 



*r> 



CLOCK SIGNAL CIRCUITS 



135 



1 00 pf > 



;x> 




U! 



-DH> 



C Q 



<— £x>— J— ^O— I 



1/3 MC7404 




ADJUSTABLE CLOCK FOR MPU— Two MC8602 
cross-coupled mono MVBRs with individual 
pulse-width adjustments are used as clock os- 
cillator to provide frequency flexibility for ex- 
perimentation with data throughput, real-time 
operation with interrupts, and diagnosis of sys- 
tem timing problems. Required nonoverlapping 
clock pulses for phases 1 and 2 are generated by 
propagation delays through MVBRs. Transistor 
pairs used for drivers are MPQ6842. — "Micro- 
processor Applications Manual" (Motorola Se- 
ries in Solid-State Electronics), McGraw-Hill, 
New York, NY, 1975, p 4-5-4-10. 



33 pf I — - 

i— e-VA* * 



RC CLOCK — Simple TTL clock generator is suit- 
able for most TTL systems. Requires only half 
of hex inverter package and three passive com- 
ponents. Clock frequency depends on value of 
C: 200 pF gives 5 MHz; 1600 pF gives 1 MHz; 
0.018 pF gives 100 kHz; and 0.18 pF gives 10 
kHz. — Circuits, 73 Magazine, Aug. 1974, p 99. 



MPU 02 and 
DBE 




w* 



CRYSTAL-CONTROLLED TIMER— Intersil 7209 
crystal oscillator provides buffered CMOS out- 
put capable of driving over five TTL loads at any 
crystal frequency up to 10 MHz. Used in appli- 
cations requiring high-accuracy buffered timing 
signals for system clocks. — B. O'Neil, IC Tim- 
ers — the "Old Reliable" 555 Has Company, BDN 
Magazine, Sept. 5, 1977, p 89-93. 



390pF 




CMOS FOUR-GATE CLOCK— Only one 4001 
CMOS quad two-input NOR-gate IC is needed 
for symmetrical complementary-output clock 
having good temperature and supply stability. 
Gates U, and U 2 form astabie oscillator produc- 



I 



I00i 



I 



ing positive-going pulses used to trigger divide- 
by-2 flip-flop U3-U4. Circuit will operate over 
wide range of supply voltages and tempera- 



tures. — M. Eaton, Symmetrical CMOS Clock Is 
Inexpensive, EDN Magazine, March 20, 1974, p 
80 and 83. 



136 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



SET FOR 

800Hz 

WITH NO INPUT 



FROM 

FSK 

DETECTOR 




OUTPUT 
800Hz 



TO 
O FSK 
GENERATOR 



800-Hz CLOCK FOR CASSETTE RECORDER— 
565 PLL is set for free-running at 800 Hz with no 
input. When data pulses extracted from FSK re- 
corded data on cassette tape are fed in, clock is 
synchronized to data and stays in sync for up to 
seven 0s in succession. — "Signetics Analog 
Data Manual," Signetics, Sunnyvale, CA, 1977, 
p 859-860. 



ru^i 



OUTPUT 
FROM ,jA710 

800 Hz CLOCK 



60-Hz GLITCH-FREE CLOCK— Circuit generates 
complementary gated 60-Hz clock pulses that 
are always wider than 2 /ts, without glitches 
even if gate is enabled or disabled during clock 
pulse. Accuracy depends on stability of power- 
line frequency. — R. I. White, Gated 60 Hz Clock 
Avoids Glitches, EDNIEEE Magazine, Nov. 1, 
1971, p 52. 




2 usee 




DRIVER FOR 24 MOS REGISTERS— With input 
of clock pulses preshaped to width of about 150 
ns, circuit shown will generate 17-V 1 .5-A clock 
signal required for driving 1024-bit serial MOS 
memories or shift registers. Article traces op- 
eration of circuit. All diodes are 1N3064. — R. D. 
Hoose and G. L. Anderson, Clock Driver for MOS 
Shift Registers, EDNIEEE Magazine, Dec. 15, 
1971, p 56-57. 



CLOCK SIGNAL CIRCUITS 



137 



+ V CC (8-I5V) 



2.5-kHz CLOCK— Requires only 3-mW power to 
generate fast 15-V two-phase rectangular 
pulses with 1 0O-ns widths and 20-ns rise and fall 
times. Suitable for many MOSFET shift regis- 
ters. Uses two D13T1 programmable UJT oscil- 
lators, each having four-transistor driver stage 
using 2N2369 transistors. Oscillators are cross- 
synchronized by 130-pF capacitor. Timing and 
bias networks of UJTs set pulse repetition fre- 
quency. — G. A. Altemose, Low-Power Two- 
Phase Clock, EDNIEEE Magazine, May 15, 1971, 
p49. 




A WV 



n n_ 



AH U IT 



d n n n_ 

<p — U U IT 



OSCILLATOR 
OUTPUT 



FF, OUTPUT 12V 



"i r-L-T 

^ n n 



0', 



(a) 



id LJ LJ 

-H T *2 h- 

■^ n n. 



G,.G 2 ,G 3 . FF,,FF 2 -OPERATE AT 12V dc 
G 4 , G 5 - OPERATE AT 5V ac 



15 MS! 
■VW- 



3Z> 



80 



■#■ 



'25pF 



TOOTHER 
TIMING CIRCUITS 



TTL LEVE 



^ 



r 



r 



fc 2 

'60pF 



TWO-PHASE CLOCK FOR 8080— Crystal oscil- 
lator operating at twice desired clock frequency 
uses pi network R,-C 1 -X,-C 2 providing 180° 
phase shift required for positive feedback to 
input of oscillator G, . D flip-flop FF, in divide-by- 
2 configuration generates one phase, while 
NOR gate G : generates other phase from basic 
oscillator by masking out every other cycle. G 3 
merely provides enough propagation delay on 
second phase to prevent overlap with first 
phase. Crystal should be below 3 MHz. — D. M. 
Risen, 8080 CMOS Clock Uses Two IC's, EDN 
Magazine, Jan. 5, 1977, p 50. 



n 



s 

D Q 

FF ' _ 
CLK Q 
R 



S 

Q D 

FF, 



Q CLK 
R 



F„/2 



T35H 



^E> 



■*■ »i 




TTL 
LEVEL 



(b) 



G, . G 2 , G 3 - CD4002 QUAD NOR GATE 

FF,, FF 2 -CD4013DUALD-FLOPS 

G 4 , G 5 - CD4050 HEX BUFFER 



138 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



ICI 
7404 



560 a 
-WV- 



POINT 
A 



^m>^ 



02«iF 



I 





2.0MHz CRYSTAL 






+ SV 


ICI 


7404 


14 


IC2 


7474 


14 


IC3 


7400 


14 


IC4 


74103 


4 



6 NO 

7 
7 
7 
II 



1 



PR 
D 

IC2o 
CLK 

7474 



D 



RW 
(FROM 6502) 



♦ 5 

1 



PR 


IC2b 
CLK 
7474 



ry 



POINT 
C 



IC3 
, 7400 

.-*!>« — o 



SPEED SELECT 



♦ 



(INPUT TO 

6502) 
PIN 37 



J 

IC4 
CLK 
74103 



IC3 
7400 



(TO SLOW 
2102' t) 



TWO-SPEED CLOCK— Creates alternative slow 
clock cycle for MOS Technology 6502 processor 
on KIM-1 microcomputer card under control of 
SPEED SELECT line generated by slow memo- 
ries. Control logic of gives fast cycles, while 



logic 1 gives slow cycles. Processor cycle is 
maintained for 1 /us for fast memory access, but 
cycle is automatically stretched to 2 /is for 
slower 2102s. — Y. M. Gupta, True Confessions: 
How I Relate to KIM, BYTE, Aug. 1976, p 44-48. 



R2 
82 



G| a G2 FAIRCHILD 90I6 
HEX INVERTER 



IOpH 



Rl 
82 



— ^C 2 
To.05 T0.005 

» liF *MF 



Rs 
82 



Jg^o-I — w — |g^» 



TWO-INVERTER COLPITTS— Simple low-cost 
clock uses two inverters in LC circuit. G, oper- 
ates as Colpitts oscillator, with C, setting feed- 
back level and L,-Ci setting frequency. Low DC 
resistance path through R„ R 2 , and L, provides 
high negative DC feedback around d and 
biases it into linear region. G 2 squares output of 
G, to appropriate TTL levels. For values shown, 
output period is 1.2 /us and rise and fall times 
are under 20 ns. — C. A. Herbst, TTL Inverter 
Makes Stable Colpitts Oscillator, EDNIEEE Mag- 
azine, May 15, 1971, p 50. 



+12V 



+5V 




TiO 



13| J0-| A+12V 



74S11 



■OSC(TTL) 
-«,ITTLI 

- 0,01X1 



74S00 



R i2 180 

-9V4-VW 1, 




-vw-« * 

d, -f ;s c w 

1N4002I < i 01 j 



TWO-PHASE CLOCK FOR 8080— Typical clock level translation in combination with 32-MHz Buy or Build? EDN Magazine, Sept. 20, 1975, p 
design for Intel 8080 microprocessor system crystal to generate two-phase 12-V clock wave- 53-55. 
uses carefully designed logic sequence and form. — S. G. Brannan, jxP Clock Generators — 



CLOCK SIGNAL CIRCUITS 



139 



DC From 
Primary q_ 

Power Source 



Backup 
Battery ^ 
Powei 



1 



-w- 



-w- 



lokn 



R, 
1.2 Mil 



c, 

0.01 uF 



4-3 V rms — v^_ 
(60 Hz) 22 kn 



C,* 
1 M F 



o 



R 
TH 



V+ 
555 



+5Vto 
Remainder 
of System 



— — o Output 
(60-Hz Square Wave) 



-LC, 

0.01 ; 



BATTERY BACKUP POWER— Provides 60-Hz 
square-wave output for driving electronic 
timekeeping circuits from battery during AC 
power failure. 555 timer is connected as square- 
wave astable MVBR normally locked to incom- 
ing 60-Hz power frequency. R t should be 
trimmed for zero beat with 60-Hz source. When 
primary power fails, reference voltage disap- 
pears and effect of C, on frequency is mini- 
mized. 555 now oscillates at frequency deter- 
mined by R, and C„ which is 60 Hz. Use 6-V 
battery. — W. G. Jung, "IC Timer Cookbook," 
Howard W. Sams, Indianapolis, IN, 1977; p 201- 
203. 



*C, > C,. Choose R, for > 1/3 V+ p-p across C,. 



vcc 



vcc 



SYNCHRONIZER— For each switch closure, cir- 
cuit produces one output pulse that is one clock 
period wide, synchronized with clock. When 
switch is closed, debouncing latch using 7400 
gates goes high and makes flip-flop B high. Next 
clock pulse makes flip-flop C high and resets 
flip-flop B. At next clock pulse, flip-flop C goes 
low to complete cycle of operation. — E. E. Hriv- 
nak. House Cleaning the Logical Way, 73 Mag- 
azine, Aug. 1974, p 85-90. 




»00 




(1,4 


1 1 — 
FF 


A't> 


FF 






D " 

1/2 
7474 


B 




1/2 
7474 

t c o 


C 


*n a 


5 




12 


9 

c" 


A 3 






II 


s 




— 


V' 






<■»•» 






1 





















1/6 7404 



n_ 



FF B 



FF C 



SELECT FOR OPTIMUM 
FREQUENCY ACCURACY 
<SEE TEXT) 




V 



NOTE < ALL PARTS ARE LOCATED 
ON THE COUNTER BOARD 



U6 
74L90 



12 &3 



-*QC (STROBE) 



TO 



l4 \ "\ 



U7 
74L90 



nil i \ v r' 



12 10 



74100 
iU3c 



GATING 
CIRCUITS 
C (NOT CLOCK) > a MULTI- 
PLEX 
CONTftOL 
CIRCUIT 

CI CLOCK I 



counts, and displaying result. — M. A. Chapman, 
10-Hz CLOCK — Stable and accurate clock is meter receiver as part of digital display system High Performance 20-Meter Receiver with Dig- 
generated by high-precision 100-kHz crystal os- that shows frequency of received signal after ital Frequency Readout, Ham Radio, Nov. 1977, 
cillator and decade divider chain. Used in 20- counting HFO, LO, and BFO outputs, summing p 56-65. 



140 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



CON TROL,™ ^, 47 „ 0.1„F 39k> R 




555 3 
ASTABLE 
2 6OH2 



► OUTPUT 



I OSCI LLATOR 
OUTPUT 



VTR CLOCK — Locked oscillator using only two- 
input NAND gate and 555 timer provides logic 
clock signal for videotape recorder. Vertical 
sync signal, stripped from video information re- 
corded on tape, is used as control signal. C, con- 
trols locking range for free-running frequency of 
555. When C 2 is charging (555 output is high), R 2 
and D, determine time constant T,. During dis- 
charge of C 2 , D, is reverse-biased and discharge 
time constant T 2 is determined by R 3 and R 4 . — 
L. Saunders, Locked Oscillator Uses a 555 
Timer, EDN Magazine, June 20, 1975, p 114. 



. x CD4009A 



COM 




CLOCK FOR REGULATED SUPPLY— Single RCA 
CD4009A serves as clock generator and mono 
for driving regulated power supply having fold- 
back current-limiting protection. R, c and C te are 
major frequency-determining components. R s 
should be made equal to or greater than 2R K . 
Article gives equation for period T of oscillator, 
which ranges from about 2.2 to 2.5 times 
RtcCtc- — J. L. Bohan, Clocking Scheme Improves 
Power Supply Short-Circuit Protection, EDN 
Magazine, March 5, 1974, p 49-52. 



FOUR-PHASE CLOCK— Provides expandable 3- 
bft binary output and four overlapping clock 
pulses for each unique binary output. A-output 
of 7493 binary counter is used along with clock 
input to form four-phase overlapping clock 
function. Article includes timing diagram that 
shows sequence of output pulses. Developed 
for use in addressing multiplexers, ROMs, and 
other digital units. — B. Brandstedt, Clock Pulse 
Generator Has Addressable Output, EDN Mag- 
azine, Dec. 15, 1972, p 42. 



INPUTi 

o 



r 



£ 



4-BIT BINARY COUNTER B 



7493 




1/6 7404 
INVERTER 



TO NEXT COUNTER 
WHEN REQUIRED 



PROVIDES THE 

ADDRESS 

DURING 

EACH OF WHICH 

4 OVERLAPPING 

CLOCK 

PULSES OCCUR 




1/6 7404 
NVERTER 



"1 I , J I. 740! 

FT Qtfc 

6"4" 6"1" J"2" 



4-PHASE CLOCK OUTPUTS 




TRANSISTOR-STABILIZED CMOS FOUR-GATE 
CLOCK— Addition of 2N2222 transistor to clock 
using 4001 CMOS quad two-input NOR-gate IC 
boosts temperature stability to 0.05%/X and 



supply stability to 0.05%/V. Transistor circuit 
differentiates output signal of oscillator U,-U s 



ioopf 3; 



100pF 



r 

I 



and provides pulses for toggling flip-flop U 3 - 
U 4 . — M. Eaton, Symmetrical.CMOS Clock Is In- 
expensive, EDN Magazine, March 20, 1974, p 80 
and 83. 



CHAPTER 13 

Code Circuits 



Covers Morse-code circuits as used in amateur, maritime, and other CW 
communication applications for keyers, monitors, code generators and 
regenerators, decoders, practice oscillators, CW filters, and call-letter 
generators. For circuits capable of handling CW along with other types of 
modulation and for circuits handling other types of codes, see also Filter, IF 
Amplifier, Keyboard, Memory, Microprocessor, Single-Sideband, Receiver, 
Transceiver, and Transmitter chapters. 



DETECTOR 



AF AMP 



AF OUTPUT 






) n/ l/V T ' | AUDIO < 





EXCEPT AS INOICATEO, DECIMAL 
VALUES OF CAPACITANCE ARE 
IN MICROFARADS t JjF I ; OTHERS 
ARE IN PICOFARADS I pF OR jiJiF); 
RESISTANCES ARE IN OHMS', 
k -1000, M.1 000 000 

POLY -POLYSTYRENE 
I 1 -DC V 



CR1 - CR3, incl. — High-speed switching 
diode (Radio Shack type 276-1620). 

J1 — RCA-type phono jack. 

J2 — 1/4-inch phone jack. 

J3, J4 — Binding post. 

L1 — 3 turns insulated hookup wire wound 
over (ground) end of L2. 

L2 - Radio Shack type 273-101 rf choke. 
Tap at 4 turns above ground end. 

40-METER DIRECT-CONVERSION— Simple, 
foolproof circuit design uses discrete compo- 
nents mounted on printed-circuit board shaped 
to fit in oval herring can. Single 7-MHz RF stage 
and voltage-tuned VFO feed product detector 



. 5000 

'MAIN TUNING 

L3 - Radio Shack type 273-101 rf choke. 
L4 — 4 turns insulated hookup wire wound 

over cold end of L3. 
L5 — 5 turns insulated hookup wire wound 

over ground end of L7. 
L6 — 4 turns insulated hookup wire wound 

adjacent to high end of L7. 
L7 - Radio Shack type 273-101 rf choke with 

six of the original turns removed. 

02 that drives 2-stage AF amplifier having peak 
response at about 650 Hz for most comfortable 
CW listening. VFO uses Armstrong or tickler- 
feedback circuit, with CR1 and CR2 connected 
as voltage-variable-capacitance diodes. Zener 



L8 - Radio Shack type 273-102 rf choke. 
Q1 , Q5 - JFET (Radio Shack type 

RS-2035). 
Q2 - Q4, incl. — Transistor (Radio Shack type 

276-1617). 
T1 — Audio transformer (Radio Shack type 

273-13781. 
T2 — Audio transformer (Radio Shack type 

273-1380). 

regulator powers VFO circuit for good fre- 
quency stability. Receiver will tune any 100-kHz 
segment of 40-meter band. — J. Rusgrove, The 
Herring-Aid Five, QST, July 1976, p 20-23. 



141 



142 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




5,/F 



390 n 

tk 

-A-w- 



#22 WIRE 



7. 



"1.5 V 



811 



UP TO 200 FT. 



<M 



«1 






MORSE-CODE SET— National LM3909 flasher 
IC is connected as tone oscillator that simulta- 
neously drives loudspeakers at both sending 
and receiving ends of wire line used for Morse- 
code communication system. Single alkaline 
penlight cell lasts 3 months to 1 year depending 
on usage. Three-wire system using parallel tel- 
egraph keys eliminates need for send-receive 
switch. Tone frequency is about 400 Hz. — "Lin- 
ear Applications, Vol. 2," National Semiconduc- 
tor, Santa Clara, CA, 1976, AN-154, p 5-6. 



CQ ON TAPE — Frequently used code message 
such as amateur radio CQ call is recorded by 
keying audio oscillator with desired message 
and picking up oscillator output with micro- 
phone of endless-loop cassette or other tape re- 
corder. Rewound recording is played back 
through single-transistor stage connected as 
shown for driving keying relay of transmitter. 
Circuit requires shielding. — Circuits, 73 Maga- 
zine, July 1977, p 34. 



TRANSMITTER 



CD= 




^^h 



XD^i 



IC legend 




A, B, C, G - CD4001 




I, L, M, N - CD4001 




D, H, F, P- CD4011 




E.J, K. 0-CD4011 




FF,. FF2-CD4027 




FF 3 . FF4 -CD4013 


D, 




1N914 



33QSJ< 



<■! K, 




FCEE 



-k^r 



> R 2 
>10K 




KEYER WITH MEMORY— Includes sidetone os- 
cillator and dash-dot memory along with vari- 
able speed, automatic spacing, and self-com- 
pleting dots and dashes. If dot paddle is pressed 
and released while keyer is generating dash, dot 
is generated with correct spacing after dash is 



completed. Gates A, B, and C form gated MVBR. 
Gates D, E, O, and P serve to complete charac- 
ters. JK flip-flops FF, and FF 2 , D flip-flop FF 3 , and 
gates F, G, and L provide character-shaping re- 
quired for dash-dot memory using gates M, N, 
and RS flip-flop FF„. Gates J and K generate 



audio sidetone. K, is B & F Enterprises ERA- 
21061 SPST reed relay. Supply can be 9-V bat- 
tery. — T. R. Crawford. A Low-Power Cosmos 
Electronic Keyer in Two Versions, CQ, Nov. 
1975, p 17-24. 



CODE CIRCUITS 



143 



yiN9l4 ^ 100 F F 
♦ IN9I4 




4-OR I 
OHM 
45n SPKR. 




9 V 
+ 1,1,-- 



'1 



L-l L-AAA^i 







KEYER — Uses gating and flip-flop functions to 
generate dots and dashes under control of 
gated clock. SN7413 Schmitt trigger is con- 
nected as relaxation oscillator. Circuit provides 



minimum spacing between dots and dashes re- 
gardless of paddle movements. — A. D. Heff rick, 
A Simple IC Keyer, 73 Magazine, Dec. 1973, p 
37-38. 



TIMER FOR CODE PRACTICE— Signetics 
NE555V timer operating on 9-V supply serves as 
AF oscillator providing adequate volume for 
classroom instruction. Output tone can be var- 
ied from several hundred to several thousand 
hertz. — J. Burney, Code Practice Oscillator, 
QST, July 1974, p 37. 



DRIVER 



0+12V 



AF 
PREAMP 




TO 

PROD , 1+ 

DET 0-f-)P 




EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS I JiF ) ; 
OTHERS ARE IN PICOFARADS ( pF OR jijiF); 
RESISTANCES ARE IN OHMS', 
k> I00O, M.IOOO 000. 



POLY. . POLYSTYRENE 



FL5 

RC ACTIVE 

750-Hz CW 

FILTER 



¥^^>* 



3.5 W FOR CW — Discrete devices minimize dis- 
tortion and eliminate fuzziness while listening 
to low-level CW signals in communication re- 



ceiver covering 1.8-2 MHz. RC active bandpass 
filter peaked at 800 Hz improves S/N ratio for 
weak signals. Adjust BFO of receiver to 800 Hz. 



Two-part article gives all other circuits of re- 
ceiver.— D. DeMaw, His Eminence— the Re- 
ceiver, QST, Part 2— July 1976, p 14-17 (Part 
1— June 1976, p 27-30). 



144 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



SENSOR KEYER— Skin resistance of about 10K 
creates dashes when finger touches grid pat- 
tern on left side of paddle and dots when other 
finger touches pattern on other side. Transis- 
tors act as solid-state switches. Developed for 
use with Heath kit CW keyer HD-10. Supply is 10 
V, obtained from 10-V zener connected through 
appropriate dropping resistor to higher-voltage 
source. Article covers construction of paddle by 
etching printed-wiring board. — T. Urbizu, Try a 
Sensor Keyer, 73 Magazine, Jan. 1978, p 184- 
185. 



i( 



° TO DOTS 
IN KEYER 



Q2 
2N2222 




P 




nnnn_£_, 



2N4124' 



39k 
-AA/V " 



2200 
-AAA ' 



EXCEPT AS INDICATED, DECIMAL 
VALUES OF CAPACITANCE ARE 
IN MICROFARADS (jiF); OTHERS 
ARE IN PICOFARADS (pF OR jjjiF); 
RESISTANCES ARE IN OHMS; 
k-IOOO,M«IOOOOOO 




TORF 

Wr-oourgrr 
(son) 



TO SPEAKER/ 
HEADPHONES 
4-50/\ 
NOT CRITICAL 



AF OSCILLATOR MONITORS CW— Can be 
added to any transceiver not already having 
built-in sidetone oscillator, to hear keying of 
transmitter. RF input from transmitter is recti- 
fied by CR1 to provide about 6-VDC supply. Key- 
ing of carrier on and off turns NE555 AF oscil- 
lator on and off correspondingly. — J. Arnold, A 
CW Monitor for the Swan 270, QST, Aug. 1976, 
p44. 



SIDETONE OSC. 



CQ CALL SYNTHESIZER— Uses only two Sig- 
netics 8223 256-bit PROMs for storing up to 
2048 bits of code information, for automatic 
generation of Morse-code CQ calls, test mes- 
sages, and other frequently used messages. Re- 
peated words are stored in only one location 
and selected as needed, to quadruple capacity 
of memory. PROMs can be programmed in field 
or custom-programmed by manufacturer. 
Speed and timing of code characters are deter- 
mined by UJT oscillator Q1, variable from about 
4 to 40 Hz or 5 to 50 WPM. CR1 and CR2 are 
Archer (Radio Shack) 276-042 orequivalent. CR3 
is 1N34A, 1N270, or equivalent germanium. Q1 
is Motorola MU4891 or equivalent. Article de- 
scribes circuit operation and programming in 
detail. — J. Pollock, A Digital Morse Code Syn- 
thesizer, QST, Feb. 1976, p 37-41. 



CODE CIRCUITS 



145 






IM 220k 



Jl 



JP 



IN9M 
"CB2 
■ W9M 




-_rLnj-LrLn_ru 



DASH GENERATOR 



C04OI3 

( 
ff C S 



OT 



CD40I3 

1 
S C ff 



•W 




"31 Y? 

2IC040H 



KEYING 
2N4IZ4 SWITCH 



. 2N3440 ^^ TO XMTW 
" ) KEWWG 

CJBCUfT 




CMOS KEYER — Draws only 0.4 mA on standby 
and 2 mA with key down if supply is 10 V. Will 
work properly with 4 to 15 V. Features include 
self-completing dots, dashes, and spaces, along 
with sidetone generator and built-in transmit- 
ter keying circuit. Ratio of dashes to dots is 3: 1, 
and space has same duration as dot. Time base 
of keyer is generated by NOR gates U2C and 
U2D connected as class A MVBR. Frequency of 
oscillator is inversely linear with setting of RI. 
Inverter U3D buffers oscillator and squares its 
output. Flip-flop U6B divides frequency by 2 and 
provides clock source with perfect 50% duty 
cycle. Once enabled, gates ensure completion 
along with following space. Article gives power 
supply circuit operating from AC line and 12-V 
battery.— J. W. Pollock, COSMOS IC Electronic 
Keyer, Ham Radio, June 1974, p 6-10. 



SIDETONE MONITOR— Mostek MK5086N IC is 
used with crystal in range from 2 to 3.5 MHz as 
signal generator driving FET audio amplifier. 
Switch S1 gives choice of four AF tones, deter- 
mined by dividing crystal frequency in hertz by 
5120 for T1, 4672 for T2, 4234 for T3, and 3776 
for T4. Can also be used as code practice set and 
as audio signal generator. — J. Garrett, A Side- 
tone Monitor-Oscillator-Audio Generator, QST, 
June 1978, p 43. 




FOUND IN 
NG CIRCUIT 



©- 



/*" 



-Jr 1 



2 



LED 



L 



REGENERATED CW— Audio oscillator whose 
frequency can be varied is keyed in accordance 
with incoming CW signal, to give clean locally 
generated audio signal without background 
noise and interference. NE567 phase-locked 



■**¥*♦ 



I ''- 



—W\~ • 



HEADPHONE 






rfl't-sn 

pUJ SPEAK! 



,0PT0-IS0L4T0R 



_)J 



loop serves as tunable audio filter and LED 
switch driver for activating NE555 variable-fre- 
quency tone oscillator. LED serves as visual tun- 



ing aid to indicate that PLL is locked on to 
incoming signal.— Regenerated CW, 73 
Magazine, Dec. 1977, p 152-153. 



146 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




PRODUCT DETECTOR— Designed for use in 40- 
meter CW direct-conversion receiver, in which 
oscillator input is from 3.5-4 MHz VFO. U1 is 
RCA CA3046 transistor quad. Circuit provides 
bias stabilization for constant-current transis- 
tor and some amplification of AF output. T1 is 
audio transformer. — A. Phares, The CA3046 IC 
in a Direct-Conversion Receiver, QST, Nov. 
1973, p 45. 



TONE DECODER — Decodes audio output of am- 
ateur radio receiver. Resulting audio tone burst 
corresponds to CW signal being received, with 
tone frequency varying with receiver tuning. 
Center frequency of NE567 phase-locked loop is 
adjusted with R1 . Audio is translated into digital 
format of 1s and Os, with tones for Os. Output 
can be fed into computer for automatic trans- 
lation of Morse code and printout as text. — W. 
A. Hickey, The Computer Versus Hand Sent 
Morse Code, BYTE, Oct. 1976, p 12-14 and 106. 




Rl 

5000 

FREQUENCY 

ADJUST 



m 



6800 < ,-i-n /tn 

T |4.7 M F I 22MF 



OSCILLATOR ! 

vw-t 2 wv— * — r 



R7 * 



PUSH-PUSH DOUBLER 



-0+12V 




14 


. u . 


1 


13 


• • 


2 


V? 


• • 


.1 


11 


• • 


4 


10 


• • 


f, 


9 


• • 


S 


a 


• • 


1 



C4 — 35-pF air variable (Millen 26035 or 

Hammarlund HF-35). 
C5 — 16-pF air trimmer, pc-board mount 

Johnson 187-0109-005. 
CR1 — Silicon high-speed switching diode, 

1N914 or equiv. 
L6 - Slug-tuned inductor, 3.6 to 8.5 /uH (Mil- 

BFO FOR 20 METERS— Uses CA3045 transistor 
array, with U2A as series-tuned Clapp oscillator 
covering 7-7.2 MHz. Tuned emitter-follower 
U2B provides push-pull drive at 7 MHz to bases 



>• PIN 4 

TO 330-OHM 
RESISTOR 

ler42A686CBI or equivalent). Use shield 
can (35-mm film canister or Miller S-33). 
L7 - Toroidal inductor, 0.9 >M. Use 12 turns 
of No. 24 enam. wire on a T50-6 toroid 
core. (See QST ads for toroid suppliers — 
Amidon, G. R. Whitehouse and Palomar 
Engrs.). 

of push-push doubler U2C-U2D. Output of BFO 
is applied to product detector rather than to 
mixer of receiver. Audio signal from detector is 
frequency difference between BFO and incom- 



+12V 

P- POLYSTYRENE 
• -PHASING 
O'RMS VOLTAGE 
r~J ■ DC VOLTAGE 



EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS I JiF I ; 
OTHERS ARE IN PICOFARADS I pF OR JIJlF)', 
RESISTANCES ARE IN OHMS ', 
k*1000, M»1000 000. 

R2 - Optional circuit (see text). 10,000-ohm 

linear-taper composition control. 
T1 — Trif ilar-wound trans. 2 iM, 20 turns, 

twisted six turns per inch. No. 28 enam. 

wire on a T5Q-2 toroid core (see text). 
U2 - RCA CA3045 array IC. 
VR1 - Zener diode, 9.1 V, 1 W. 

ing signal, typically 700 Hz for CW reception. 
Article covers construction and adjustment. — 
D . DeMaw, Understanding Linear ICs, QST, Feb. 
1977, p 19-23. 



CODE CIRCUITS 



147 




KEYER WITH DOT MEMORY— Features include 
self-completing characters, exact timing of 
characters, and dot memory. Timing circuit 
uses 74121 mono MVBR U1, serving dot gen- 
erator and output stage U2A, dot memory U2B, 
and dash generator U3A-U3B. U2 and U3 are 
7473 dual JK flip-flops. Length of timing pulse 
is determined by R1-C1, with R1 controlling 



speed of keyer. Pulse-width stability at all 
speeds is better than 5% between first and all 
following pulses. Dot memory U2B allows key- 
ing of dot at any time, even if dash has not yet 
been completed. Dot is held in memory and 
keyed out automatically after dash. Diodes are 
1N914.— J. H. Fox, An Integrated Keyer/TR 
Switch, QST, Jan. 1975, p 15-20. 





■ 




















_RFC_ 








«y. 


.1 
11 
















)\ 










E 


<- 


-\c 










0. 


h 


B 
















s.OI 












01 












)\ 









fcr 



CODE MONITOR— Works with any transmitter, 
regardless of type of keying. Use any good PNP 
transistor. With NPN transistor, reverse con- 
nections to diode. Frequency of tone gets 
higher as resistance of 250K pot is reduced. 
Monitor is turned off at minimum resistance. 
Enough RFto operate monitor can be obtained 
simply by connecting it to chassis of receiver or 
transmitter. — J. Smith, Yet Another Code Mon- 
itor, 73 Magazine, Sept. 1971, p 58. 



<MUTE BOX 



FROM 
VOX 
RELAY >_L 




FAST BREAK-IN— Permits operator to hear sig- 
nals even between dots while calling DX sta- 
tion, so call can be stopped if DX station an- 
swers someone else. Timing circuit ensures 
that transmitter is not producing power when 



relays open, permitting use of small high-speed 
relays. K1-K4 are common reed relays. K5 
should have contacts rated for 300 VAC at 500 
mA. — A. Pkiess, A Fast QSK System Using Reed 
Relays, QST, Dec. 1976, p 11-12. 



148 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CW CALL GENERATOR— Basic CW identifier 
uses two gates of 7400 to form starting flip-flop 
of automatic message generator. Provides ad- 
justable speed and tone, with up to 256 bits of 
storage in Harris H1256 PROM. IC2 is 555 astable 
MVBR providing clock signal for driving two 
7493 4-bit binary counters that address PROM. 
When counters reach maximum address of 255. 
next clock count makes PROM restart at ad- 
dress 0. Each address turns on tone oscillator 
for one clock period, producing one dit. Three 
addresses in row turn on tone for three clock 
periods, producing one dah. Space between 
dits and dahs of same letter is equal to one dit, 
letter space is three dits, and word space is six 
dits (2 dahs). Thus, W takes nine addresses. Ar- 
ticle describes operation in detail and tells how 
to modify circuit for use as RTTY message gen- 
erator. — R. B. Joerger, PROM Message Gener- 
ator for RTTY, 73 Magazine, March 1977, p 94- 
98. 



TIME CLOCK 
5-50WPM 



GROUND TO TUNE o- 




• W. O + lgV 




NOTE- 

ALLPINS 14 = 1-I2V 
ALL PINS 7= GROUND 



IC NO. 



TYPE 



1,2,6 


40IIAE 


3,4,5 


40I3AE 


e 


4001 AE 


7 


4023AE 



eration, as with Heathkft HW-7 transceiver. Will 
operate directly from 3-15 V batteries of QRP 
CMOS KEYER— Features include seri-complet- automatic character spacing, all achieved with transceiver, without regulation. — G. Hinkle, 
ing dots and dashes, dot and dash memories, low-power CMOS digital devices that are com- The QRP Accu-Keyer, 73 Magazine, Aug. 1975, 
iambic operation, dot and dash insertion, and patible with low-power (QRP) transceiver op- p 58-60. 



CODE CIRCUITS 



149 



INPUT 
8-600SI RS 



« — HS + ... ^ 

to}— -W*— a • u A 74 7 

% 50K Jct J -> 



33 

M 500 CT: 8 

-?H MINIATURE 

OUTPUT 

I6JI 




-I2VO- 



OUTPUT SHOWN 
FOR I6S1.USE 
FULL PRIMARY 
FOR 8fl 



CW FILTER — Simple single-section parallel- 
tuned active filter uses negative-impedance 
converter or gyrator to replace hard-to-get in- 
ductor of passive code filter. Capacitor CL is gy- 
rated from 0.0332 jmF to effective inductance of 
1.87 H. Filter has 6-dB gain at resonance and es- 
sentially zero output impedance. Bandpass is 85 
Hz centered at about 865 Hz. Uses single -12 V 
supply. Resistors R are 7.5K, matched to about 
2%.— N. Sipkes, Build This CW Filter, 73 Mag- 
azine, June 1977, p 55. 



100 +9.1v. From 
|+ _. . V.F.O. Supply 



10 K 




To Audio Gain 
Control 



REGENERATIVE CW FILTER— Can be added be- 
tween product detector and volume control of 
SSB receiver or transceiver that does not have 
CW filter. Just before oscillation occurs, gain 
becomes extremely high with very narrow 
bandpass. Regeneration and bandpass can be 
adjusted as required. Filter typically has 40-Hz 
bandwidth centered on 800 Hz. — R. A. Yoe- 
mans. Further Enhancing the Yaesu FTDX-560 
Transceiver, CO, July 1972, p 16-18 and 20-22. 




-OAUDIO OUTPUT 



^°'^ I00 " F 

T» i Tie ' Tie Ti 



U2 



I 



U3 



2 



I 



U5 



7493 7493 B223 74151 



555 



Ur 



5 



U7 



+I2-I5V 



U8 



I 



IE 



<Jl 



1000 
*F 



PROM CW IDENTIFIER— Call letters stored in 
8223 PROM U3 drive 74151 multiplexer/data se- Timed holdoff keeps identifier from being re- of circuit and gives construction and program- 
lector U4 for keying NE555 audio oscillator U5 keyed within specified time period, with reiden- ming details. — W. Hosking, ID with a PROM, 73 
which feeds transmitter mike input through RA. trfying at end of period. Article covers operation Magazine, Nov. 1976, p 90-92. 



150 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 24 v. o- 

150 K 

To Output ^ 3K 

fromTope ^2 



/Recorder °-J 




input 6 a 




+ 6v.£- 



+ 6v.f- 



-■ C DATA 



T T 



LOAQ RECIRCULATE 



RECORDED-CODE KEYER— CW message re- 
corded on cassette tape with keyed tone gen- 
erator is played back for keying transmitter with 
frequently repeated messages. Transmitted 
signal is essentially perfect reproduction of re- 
cording. Automatic transmission can be 
stopped at any point by tapping hand key; this 
deactivates tape recorder for manual keying of 
transmitter. All transistors are 2N2222 or equiv- 
alent BCY58. Use 24-V reed relays with 1K coil 
resistance. Pilot lamps are 24 V rated up to 3 W. 
CR, is silicon diode. Whenever recorder emits 
beep, positive signal appears at base of Q 2 , mak- 
ing it conduct and activate K, whose contacts 
go to key jack of transmitter. — A. Day, An Audio 
Tape-Controlled CW Keyer, CO, Nov. 1971, p 
31-32. 



PLL CODE REGENERATOR— Permits comforta- 
ble listening to CW signals deeply embedded in 
noise, hash, and interference, by detecting one 
particular CW transmission and keying inde- 
pendent oscillator with its signal. Consists of 
signal amplifier Q1, narrow-band PLL frequency 
_ t detector and trigger U1, PLL function generator 

— Pfo*f°~° U2, gate 02, and AF output amplifier U3. In ab- 
sence of triggering signal, output pin 8 of U1 
presents high impedance to ground. With trig- 
gering frequency, output presents low imped- 
ance to ground. Oscillator U2 is gated by U1 
through 02.— C. R. Lewartand R. S. Libenschek, 
CW Regenerator for Interference-Free Commu- 
nications, Ham Radio, April 1974, p 54-56. 



10K 

-AWV 1 



5 6 

ICi 



> Output 




> Output 



MANUAL CLOCK 



27 K 
-V\/\ 1 



-^+6v. 



r 



i 



->-6v : 



->-12v. 



FF, 



I 

IC2 
I 
I 



FF 2 



3 14 10 12 9 



T 



+6»- 



Imeg „ 



500K , 

SPEED * 



pj 



20K 



-^+6v 



N.O. 
I- START 



68(/f 



No. 44 r - s 

Optional I ■-'. I 
"READY" light \.L' 



IK 



1N916 

— M— 



LiS^ 2 



200-BIT MEMORY— Drawback of volatile code- 
storing memory is offset by low cost and com- 
parative ease of programming. IC, is Signetics 
251 ID MOS dual 200-bit shift register whose 
digital levels are shifted one position for each 



clock pulse. Inverters I, and l 2 of CMOS hex in- 
verter IC 3 form variable-frequency gated 
square-wave clock oscillator controlled by state 
of flip-flop FF 2 in 74C74 CMOS dual D flip-flop. 
Shift register must first be cleared by setting 



DATA and CONTROL switches to ground and 
RECIRCULATE switch to hold, then pressing 
START button (with speed control set fast) until 
register is full of zeros. Release START button 
and switch control to +6 V for about 10 s. Now 
set CONTROL to ground and start program- 
ming. To enter dah, switch manual clock 
through three complete up-center/down-center 
cycles, switch data line to ground, and cycle 
manual clock through one cycle to insert space 
into memory. To enter dit, switch manual clock 
through only one up/down cycle. Continue until 
entire message is entered in register, switch to 
RECIRCULATE, and push START switch. Mes- 
sage will now be sent in perfect code at any de- 
sired speed. — B. P. Vandenberg, An Inexpen- 
sive Memory Keyer for Contests, CO, May 1976, 
p 50-51. 



CODE CIRCUITS 



151 




n>^n> 



Imf 
— If- 




IC legend 

A. 6, C, G - CD4001 
0, E. F, H -CD4011 
FF1, FF2-CD4027 



CMOS KEYER— Gives variable speed, auto- 
matic spacing, and self-completing dots and 
dashes. Gates C, B, and Aform gated MVBR. Dot 
paddle initiates dot by making output of gate D 
go low, while gate E goes low for dash. Char- 
acter-shaping section (gates G, H, and F with JK 
flip-flops FF, and FF 2 ) takes square pulses from 
pin 3 of MVBR gate B and gives perfectly spaced 
dots and dashes. FF, divides clock pulses by 2, 
making dot equal to one complete period of 
MVBR. FF, divides output of FF, by 2, and out- 
puts of both flip-flops are logically ORed to pro- 
vide dashes. K, is SPST reed relay. Supply can 
be 9-V battery. — T. R. Crawford, A Low-Power 
Cosmos Electronic Keyer in Two Versions, CO, 
Nov. 1975, p 17-24. 



KEYER OSCILLATOR— Oscillator or clock starts 
when key is closed and can be held until dot, 
dash, or space is completed. U1 is SN7400, and 
U2 is SN74L04. Diodes at input of U2A form OR 
gate that controls oscillator. These inputs can 
be used to keep oscillator running for self-com- 
pleting action. Time constant, set by C1 and R1, 
is 4 ms which is width of clock pulse. Values for 
C2, R2, and R3 give pulse repetition rate of 50 to 
95 ms, corresponding to about 12 to 24 WPM. 
For higher speeds, reduce values of C2 and R2. 
CR1 and CR2 are signal diodes that prevent first 
pulse from being different; 250-pF capacitor on 
output prevents noise spikes from triggering 
keyer circuits falsely. — J. T. Miller, Integrated- 
Circurt Oscillator, Ham Radio, Feb. 1978, p 77. 



OR CIRCUIT 



INPUTS FROM 
KEY CIRCUITS 
AND HOLD 



ISO TO 250pF 





|0 — + 



80-METER CW DIRECT-CONVERSION— Reso- 
nant-dipole antenna feeds directly into bal- 
anced product detector that cancels strong in- 
terfering local broadcast signals but adds 
products of mixing with local oscillator that 
covers 3490-3660 kHz for CW work. R3 is ad- 
justed only once for best performance. Only half 
of GE GEL277 dual power amplifier is used, for 
gain of 40 dB. Circuit values make AF amplifier 
resonate at 1 kHz, with 1 2 dB of attenuation per 
octave on either side of this center frequency. 
T1 should be shielded against vertical-sync 
magnetic fields of TV sets up to 60 feet away. 
T1 is transistor push-pull output transformer. 
Use twisted pair for connecting 1-1 and 2-2, to 



prevent imbalance effects. Article gives con- 
struction details for L1-L4. — B. Pasaric, A New 



Front End for Direct-Conversion Receivers, 
QST, Oct. 1974, p 11-14. 



152 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



E^ 



560* S560K S270K SlSOh 



y£y 



T 



51 ADDS- 
5 WPM 

52 ADDS- 
10 WPM 

53 ADDS- 
20 WPM 



T 



I 



r 



*T0 DIGITAL COUNTER 



OSC/LLATOR 



T 



fh 



FREQUENCY METER 




5 



D> 



w 



m. 



CW FILTER — Variable-bandwidth variable-fre- 
quency audio filter can be tuned to center fre- 
quency anywhere in range from 300 to 3000 Hz. 
Bandwidth can be as narrow as 50 Hz, which is 
about 3 times theoretical minimum of 15 Hz for 
50-bit words and Morse code at 25 WPM. Per- 
formance can be improved over entire fre- 
quency range by using 741 opamp. — R. Skelton, 
Comments, Ham Radio, June 1975, p 56-57. 



KEYER SPEED CONTROL— Electronic time base 
provides direct readout of keyer speed for 5 to 
40 WPM in increments of 5 WPM by noting po- 
sitions of three speed-control switches. Vernier 
adjustment pot R1 can be used for continuous 
speed adjustment if desired. Analog frequency 
meter provides alternate direct indication of 
keyer speed on milliammeter that can be cali- 
brated in words per minute. Frequency of 



NE555 oscillator is 100 times keyer speed. Keyer 
clock is obtained by dividing oscillator speed by 
120; thus, for 24 WPM, oscillator runs at 2400 
Hz which can be read easily on digital counter. 
Time-base divider would supply 20-Hz clock fre- 
quency for 24-WPM keying. — G. Jones, Cali- 
brated Electronic Keyer Time Base, Ham Radio, 
Aug. 1975, p 39-41. 

MEMORY 
+ I2V 



SINGLE 
STEP 

PB2 
VDDO — o^ 

NORMAL 



DEBOUNCER 




CRI 

r 

IN9I4 



1.SV 



IC2 
14562 



~Ji 



RECIRCULATE 



1 



Rll 
MEG 





IC4 
4011 



IC4 
4011 



Z 



R3 

I0K 



R4 
IO0K 



C2 
.0047 



-►HI Z AUDIO 




/ LOW Z 

t *■ AUDIO 



AUDIO 
OSCILLATOR 



BUFFER 

AMP 

(OPTIONAL) 



OUTPUT 
KEY 



128-BIT CODE STORE— Draws almost no 
power, can be used on RTTY as well as CW, and 
can be reprogrammed in less than 1 min. Built 
around Motorola MC14562CP 128-bit shift reg- 
ister. Combination of 1 (high level) and (low 
level) bits forming identifier message is fed into 



memory by placing S1 in program position zero 
and pressing start switch PB1 to dump contents 
of shift register and leave only 0s. Now, set SI 
to desired first 1 or 0, push switch PB2 once, and 
repeat for rest of coded identifier. Set SI to RE- 
CIRCULATE, push PB1 to cycle back to starting 



point, and unit is ready for use. If debouncer is 
not effective, move its wire from IC1-1 1 to IC4- 
10. Easier-to-get alternate values for CI and R2 
are 0.05 pF and 1 megohm. — C. W. Andreasen, 
Programmable CW ID Unit, 73 Magazine, Oct. 
1976, p 52-53. 



CODE CIRCUITS 



153 



■0 o + izv 




^vLz^ 



COM DASH DOT 



0/-04 -2N3TO5. HEP736, «fc. 
CBI. CR2 ' S.IV/O.SW ZENER 
(HEP Z02II. etc) 
M ■ PC BOARD CONNECTION. 



10-60 WPM KEYER— Uses juA747 (pair of 
/xA741Cs in 10-pin TO-5 package). R2 adjusts 
relative length of first two dfts to provide even 
spacing. Dot-dash ratio is set by C3 and C4, with 
C4fordotand both in parallel for dash. Collector 
of C4 provides for keying positive voltage (20 V 
or less) to ground. Keying transistor will handle 
up to 50 mA without heatsink. Characters are 
self-completing. Used with low-power trans- 
ceiver. — H. F. Batie, Introducing the Argomate, 
Ham Radio, April 1974, p 26-33. 



KEYER WITH TR CONTROL— Provides auto- 
matic control of TR relay for break-in operation. 
74221 TTL retriggerable mono MVBR forms 
dots or dashes, with paddle selecting side of IC 
that puts out pulse. Half of A2 (74123 dual re- 
triggerable mono MVBR with clear) makes 
spaces between dots or dashes. Remaining half 
of A2 acts with A3b and A3c as TR switch. — B. 
Voight, The TTL One Shot, 73 Magazine, Feb. 
1977, p 56-58. 



VFO 
sample 




500KH* 



50KHz> 



VFO CONTROL TO ±1 Hz— Used in coherent 
CW radio station to hold frequency of variable- 
frequency oscillator constant at 3550 kHz within 
1 Hz so 12-WPM signal can be handled in band- 
width of only 9 Hz for greatly improved signal- 
to-noise ratio. Sample of VFO output, squared 
by Q, and U„ goes to U 2 for mixing with 



3500.000-kHz harmonic signal from 500-kHz fre- 
quency standard, to produce 50-kHz signal ± 
undesired drift for mixing in U 3A with 50.000-kHz 
signal from standard. If there is difference in fre- 
quency, U 3A generates control voltage propor- 
tional to amount of difference, applied to var- 
actor tuning diode to pull VFO back to 3550.000 



kHz. Same process occurs in receive offset 
chain, except that standard frequency in U 3B is 
such that receiver will be 1 kHz away from de- 
sired 3550.000 kHz and produce desired 1-kHz 
audio output. — A. Weiss, Coherent CW. — the 
CW. of the Future, CO, June 1977, p 24-30. 



154 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CODE REGENERATOR— Converts noisy CW 
output of receiver into TTL 1s and Os for driving 
automatic Morse-code printer. Clipper U1 A and 
800-Hz active bandpass filter U1B feed injec- 
tion-locked 800-Hz phase-shift oscillator U3 
(National LM7401CN or Motorola HEP-C6052P). 
U1 is LM1458N or MC1458P. U2 uses part of 
LM709CN or HEP-C6103P as matched pair of 7- 
V back-to-back zener diodes. Diode detector 01 
has time constant of about 5 ms, which is short 
enough for highest Morse-code speeds. Detec- 
tor feeds LM311N or MLM311P1 voltage com- 
parator U4 which can drive TTL or DTL directly. 
National LM380N audio amplifier U5 allows CW 
signal to drive loudspeaker directly. — H. Olson, 
CW Regenerator/Processor, 73 Magazine, July 
1976, p 80-82. 



1-kHz TONE DECODER— Used as interface be- 
tween amateur CW receiver and Motorola 6800 
microcomputer to copy any code speed from 3 
to 60 WPM while adjusting automatically to ir- 
regularities of hand-sent code. Translation pro- 
gram given in article requires about 600 bytes 
of memory. Algorithm can be converted to run 
on almost any 8-bit microprocessor. Tone de- 
coder is 567 phase-locked loop tuned to center 
frequency of about 1 kHz, with bandwidth of 
about 1 00 Hz. Circuit will switch fast enough for 
most code speeds. PLL gives noise immunity. 
Optimum input level is about 200 mV. Output 
rests at +5 V, dropping near ground when tone 
of correct frequency is detected. — R. D. Grappei 
and J. Hemenway, Add This 6800 MORSER to 
Your Amateur Radio Station, BYTE, Oct. 1976, 
p 30-35. 



AUDIO 
INPUT 



30OK 
I VNA, 



O.I M F 



FROM 
RECEIVER 



€ 



t 



HEP53 



5/xF 



33011 



Rl 

I0K 2K 
-vyv — vw- 

TUNE 



.25>iF 



+ 5V 



:zmf 



TO PIA 
-a INPUT 
PIN 



IOO M F 



m 



rfi^S* 



A/VV-, 




U1 — Quad, CMOS, two-input, NAND gate 

(CD4011AE, SCL4011AD, etc.). 
U2, U7 — Quad. CMOS. two-Input, NOR pate 

(CD4001AE, etc.). 
U3 — Dual-CMOS, J-K lllp-flop (CD4027AE, 

etc.). 
U4 — Dual-CMOS, D flip-flop (CD4013AE, etc.). 
U5 — CMOS, 12-blt binary counter (CD4040AE, 

etc.). 
U6 — 1024 X 1-bit CMOS RAM (Intersil 

IMB518CJN). 



KEYING TRANSISTORS 



I . 0.0O2 

T0» E &« M0 Ki? R 



lij^^-Mj^" 



KEYER WITH MEMORY— Low-drain CMOS cir- 
cuit permits storage in RAM of message being 
keyed, for repeated later use by pushing button. 
Includes monitor, simple weight control, and 
both positive and negative keying outputs. 



Playback of stored message can be interrupted 
by closing either paddle contact. 1024-bit mem- 
ory wll hojd two runs of alphabet, two sets of 
numbers, and several punctuation marks. Dot 
is stored as 1 followed. by 0; dash is three 1s fol- 



lowed by 0. Free-running clock ensures that 
spaces will be recorded. — C. B. Opal, The Micro- 
TO Message Keyer, QST, Feb. 1978, p 11-14. 



CODE CIRCUITS 



155 





TWO-TIMER KEYER— Characters are self-com- 
pleting and fully adjustable as to speed and 
length of character. When dot key is closed, 
NE555 timer U1 becomes astable MVBR with 
speed determined by RB and dot duration by 
RA. Identical timer U2 provides longer character 
lengths for dashes. All diodes are 1N4004 or 



equivalent 400 V PIV at 1 A. Q1 and 02 are 
2N2222, 03 is 2N5964, and RL1 is 12-V reed 
relay. Capacitor values are in microfarads. All 
pots are linear. Power is not regulated. — A. 
Ring, Build the World's Simplest Keyer, 73 Mag- 
azine, May 1977, p 46-47. 



STOPPING PADDLE BOUNCE— Simple circuit 
prevents generation of erroneous dots by pad- 
dle contact bounce in keyers having dot mem- 
ory. Uses 74121 mono MVBR and 7432 AND 
gate. Output of 74121 stays low if paddle is not 
in use or if dots or dashes are being sent. Re- 
lease of dash paddle makes 74121 transmit 
high-level pulse to AND gate, long enough to 
block dot caused by bounce. Suitable only for 
keyers using +5 V. — B. Locher, Keyer Modifi- 
cation, Ham Radio, Aug. 1976, p 80. 




KEYER WITH MEMORY— Features include dot 
and dash memory, gated clock, low standby 
and key-down currents, built-in sidetone oscil- 
lator with loudspeaker, and keying circuit for 
grid-block keyed transmitter. Will operate at 



least one year on 9-V transistor battery. Article 
describes circuit operation in detail. U1 is 4011 
quad two-input NAND gate. U2 and U4 are 4081 
quad two-input AND gates. U3 is 4013 dual D 
flip-flop. U5 is 4024 seven-stage binary counter. 



V0D 

Li 

U6 is 4071 quad two-input OR gate. U7 is 4001 
quad two-input NOR gate.— E. A. Pfeiffer. MINI- 
MOS— the Best Keyer Yet?, 73 Magazine, Aug. 
1976, p 38-40 and 42-43. 



156 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



TO \ZV 
AUTO SUPPLY 



TO HORN BUTTON 




AUTOMATIC HI ON HORN— Pressing start but- 
ton of circuit momentarily makes it send letters 
HI in Morse code on automobile horn, as 
friendly signal to another ham on road. Uses 
NE555 timer as oscillator, acting with counter 
IC2, decoder IC3, power-supply latch, and reg- 
ulator. Space between four dots of H and two 
dots of I is achieved by not using pin 5 of de- 
coder. RY1 should pull in at 5 V and 16 mA max- 
imum, while RY2 should pull in at 5 V and 80 mA 
maximum and have contacts for switching 0.5- 
A inductive load of horn. — J. F. Reid, Sending 
HI, 73 Magazine, May 1977, p 90. 



TIME DELAY 
1/2 TO 5 SEC 




u - 




TO CONTROL 


K,t t 


' 


POINTS 

OR 
POWER RELAY 



Kl- SMALL +12 VOLT DC RELAY 
03 WITH CONTACTS AS NEEDED 

2N440I 



QUASI-BREAK-IN — Amateur station stays in transmit mode and stay there after last char- 
receive mode until operator starts to send code, acter is sent, for delay of several seconds (de- 
Tapping on key makes transmitter switch into termined by R1) before transmitter is deener- 



gized. Developed for use with cathode-keyed 
transmitters.— F. E. Hinkle, Jr., KOX for CW, 73 
Magazine, Feb. 1975, p 129-130. 



^ 



J 



1 



~TJ^v)° — — c£)° — 




OUTPUT ' MARK • GN0 
SPACF - 4-v 



-C2 
^S70 

R2 



Jjy GJ°V° r Jy^ 



JT 



-7H 




CMOS KEYER— Uses two CD4001 AE quad two- 
input NOR gates. Q1A-Q1B form time-base 
MVBR, and Q1C-Q1D form dash flip-flop. Three 



of remaining gates synthesize three-input NOR 
gate for dash control. Q2D controls time-base 
MVBR and provides keyer output. Speed is ad- 



justable from below 10 to over 70 WPM with 
R3. — C. J. Bader, Improved CW Transceiver for 
40 and 80, Ham Radio, July 1977, p 18-22. 



CODE CIRCUITS 



157 




lOOO^F 



U /i'D'SC DISC J, J, £ ■°' ,i X J^0J s 



KEYING OUTPUT 
POSITIVE OR NEGATIVE VOLTAGES 

/ 



CW IDENTIFIER — Circuit automatically gener- 
ates call letters for FCC-required code identifi- 
cation for FM repeaters and RTTY, when started 
by pushbutton or by pulse from other equip- 



ment. Audio output can be fed to loudspeaker 
as monitor or used to modulate FM repeater. 
Circuit shown is programmed for DE K4EEU by 
installing diodes at locations where tone is 



wanted on matrix. Article gives construction 
and programming details. — B. Kelley, A Super 
Cheapo CW IDer, 73 Magazine, Dec. 1976, p 46- 
48. 



} OUTPUT 




800 Hz ACTIVE FILTER 



~^j 567 PLL TONE DECODER 



WEAK-SIGNAL DECODER — Combination . of copying very weak signals in Morse code. LED speaker. — Circuits, 73 Magazine, July 1977, p 
narrow-bandpass 800-Hz active filter and provides visual indication supplementing con- 35. 
phase-locked loop of tone decoder permits -ventional output for headphones or loud- 




SWI 



1 



r\ iook 
-)\ — w '- 



>IMEG 



ici -'- 

.22 



•J BALANCE 



CW STEREO FILTER— Developed to enhance 
ability to read CW despite heavy contest traffic 
or other QRM. Two high-Q filters, one at each 
end of 400-Hz CW filter in receiver, create sep- 
arate audio channels to give effect of stereo. 
Transistors at outputs of channels provide extra 



I 
t 



C2 

47 F F 



IV 



:6sn 

r 



CHANNEL "B" 




current gain for driving low-impedance stereo 
headphones. CW signal at 800 Hz then appears 
to come from left, 1200-Hz signal from right, and 
in-between frequencies at various azimuth an- 
gles. Illusion of direction makes it easier for op- 
erator to concentrate on desired signal in pres- 



ence of others having slightly different 
frequencies. LI and C1 form filter for 1200-Hz 
channel, while L2 and C2 form 800-Hz filter for 
other channel. — R.L.Anderson, Stereo — a New 
Type of CW Filter, 73 Magazine, March 1976, p 
48-50. 



158 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




POINT "Z" 
DASH 8 DOT 
OUTPUT 
SIGNAL 



• FCH 191 
DTL QUAD INPUT NAND GATE 
GND 14 8 

n n n n n n n 




DI.D2- IN9I4'S 



• SN7473 
TTL DUAL JK MASTER SLAVE 



n n n n n n n 

GND 



u u u u u u u 



1 :3 DOT-DASH KEYER— Gives accurate 1 :3 dot- 
dash ratio at any desired keying speed, with 
self-completing characters. NAND gates 1, 2, 
and 3 of first FCH 191 form variable-frequency 
square-wave oscillator, with C1, R1, and R2 de- 
termining frequency. With values shown, fre- 
quency is adjustable from about 150 to 1500 Hz, 
equivalent to code speed range of about 4 to 40 
WPM. NAND gates 4 and 5 form mono MVBR. 
Flip-flops FF1 and FF2 are SN7473 TTL JK mas- 
ter-slave, acting with D1, D2, and NAND gate 6 
to generate dots and dashes. — H. P. Fischer, 
Versatile IC Keyer, 73 Magazine, Sept. 1973, p 
69-71. 



SIMPLE KEYER — Based on rapid charging of ca- 
pacitors and controlled discharge through relay 
coil. When C 2 has discharged to relay release 
voltage, relay drops out and cycle starts over 
again as long as dot side of paddle is pressed. 
Dashes are similarly formed by C,. R 4 adjusts 
speed from 10 to 40 WPM. K, is DPDT plate-cur- 
rent relay having 1K to 10K resistance. — J. J. 
Russo, An Inexpensive Electronic Keyer, CQ, 
Aug. 1971, p 58. 




5K 

DASH SPACING 



TO PIN II OF Z30 




MEMORY/CONTROL 



NPUT 

TO PIN 8 OF Z3C 

l wptJT TO PIN 12 OF Z8 




KEYER WITH MEMORY— Clock Z1 is NE555 for addressing static 256 x 1 bit RAM. To pro- again. To clear address counter if error is made, 

timer giving keying speed range of 5 to 35 WPM. gram keyer, switch to write, hit START button, or for changing message, hit RESET switch and 

Flip-flops Z2A and Z2B count clock pulses to and feed in message on keyer paddle. To send start over again.— D. W. Sewhuk, Contest Spe- 

provide self-completing dits and dahs with message back, switch to read and hit START cial Keyer, 73 Magazine, Feb. 1977, p 38. 
spaces. Z4 and Z5 are 4-bit binary counters used 



CODE CIRCUITS 



159 



ZrY>C42 ^-5k TR2 

^2_^ — © BSY 




CODE PRACTICE— Simple AF oscillator drives 
loudspeaker for producing audio tone when key 
in negative supply lead is closed. Adjust VR1 for 
most pleasing tone. — Circuits, 73 Magazine, 
July 1975. p 154. 



PRACTIGE OSCILLATOR— Simple design pro- 
vides for adjustment of both volume and 
tone. — Circuits, 73 Magazine, July 1974, p 81. 



PASSIVE CW FILTER— Uses inexpensive 88-mH 
toroids to give very sharp 35-Hz bandwidth at 
3 dB down. Filter has high insertion loss. Keyed 
waveshape has slow rise and fall, so CW signals 
have pronounced ringing that may be objec- 
tionable. — A. F. Stahler, An Experimental Com- 
parison of CW Audio Filters, 73 Magazine, July 
1973, p 65-70. 



CW SIDETONE— Audio sidetone oscillator 
serves for monitoring CW keying. Changes in 
transmitter operating frequency do not affect 
sidetone circuit. Hartley AF oscillator 02 is 
turned on by diode rectifier and DC amplifier Q1 . 
Antenna coupling shown is adequate from 160 
through 10 meters. For VHF use on 6 and 2 me- 
ters, small tuned circuit and pickup antenna are 
usually required to get enough RF input for 
monitor. Audio pitch is adjusted by changing 
value of CI. — J. Fisk, Circuits and Techniques, 
Ham Radio, June 1976, p 48-52. 




IN34A 
INPUT CIRCUIT FOR VHF 




LOW CHANNEL 



^i l )i t pv. ■■ JhMhrh^ 

■°' oi 7A , \ ,, .01 .01 74l \. 




HIGH CHANNEL 



C39k 2 20* 



? 39* < 20* 



t 



BINAURAL SYNTHESIZER FOR CW— Provides 
two channels for feeding stereo phones or two 
loudspeakers. When interference occurs a few 
hundred hertz from desired frequency, receiver 
is tuned so desired signal appears to be midway 
between loudspeakers, leaving interfering sig- 



nals at right or left. Left or low channel has low- 
pass active filter and right or high channel has 
high-pass filter, with crossover at 750 Hz. Syn- 
thesizer is designed for low-impedance drive, as 
from loudspeaker output of receiver. Resistors 
in output channels prevent oscillation when 8- 



ohm phones or loudspeakers are directly con- 
nected to outputs. Opamps will drive 2000-ohm 
phones with ample volume and give moderate 
volume levels with 8-ohm loads. — D. E. HH- 
dreth. Synthesizer for Binaural CW Reception, 
Ham Radio, Nov. 1975, p 46-48. 



160 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



TO TRANSMITTER 



WO-PADDLE KEY 




DASH 
NOTE CHASSIS AT +4.2VDC 



3-50 WPM KEYER — Uses NE555V U1 as switch- three octaves and easily drives 3-W 4-ohm loud- tion Q1-Q2 easily handles keying bias of -26 V 

able dot generator providing accurate 1:1 ratio. speaker through small transistor- radio trans- at 5 mA. — H. Seeger, Micro -TO Keyer Mods, 

SN7473 U2 forms variable dash circuit. NE555V former TR. NE555V U5 acts with U4 to provide Ham Radio, July 1976, p 68-69. 

sidetone generator U4 has tone range of about two-tone oscillator for SSB tuning. Output sec- 



CHAPTER 14 

Comparator Circuits 



Used to compare two values of voltage, frequency, phase, or digital inputs 
and provide logic output for driving variety of control circuits and indicating 
devices. See also Logic, Logic Probe, and Voltage-Level Detector chapters. 




O MSB 



■O NMSB 



L SB 



-< ANALOG 
OUTPUT 



i< 150$ 75| 



lilH IIII II IMIII II IMIMHWIIlllWllllMI I WIMWWIIIIIIIHIIIWMII 



LATCH COMPARATORS FORM 3-BIT A/D CON- ing. Comparators feed Schottky TTL binary from output glitching at conversion speeds 

VERTER— Seven Advanced Micro Devices encoder logic for encoding to 3-bit offset binary. under 12 ns.— S. Dendinger. Try the Sampling 

AM686 comparators are arranged for direct par- Quantization process is monitored by D/A con- Comparator in Your Next A/D Interface Design, 

allel conversion of rapidly changing input sig- verter. Article describes operation in detail and EDN Magazine, Sept. 20, 1976, p 91-9S. 

nals, without prior sample-and-hold condition- gives performance graphs which show freedom 



161 



162 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




VARIABLE WINDOW— Single comparator can 
be programmed for wide variety of applica- 
tions. One reference input voltage positions 
center of window, and other sets width of win- 
dow. Sum or difference of reference voltages 
must not exceed ± 10 V; if larger voltages must 
be handled, add voltage divider to scale them 



down into comparison range. A, is subtracter, 
generating voltage E b - E a for use as lower limit 
voltage. Lower limit is added to 2E b at A 2 to de- 
rive upper limit voltage E„ + E a . — W. G. Jung, 
"IC Op-Amp Cookbook," Howard W. Sams, In- 
dianapolis, IN, 1974, p 232-233. 




V, CC 

?" n 



XR-S200 

MULTIPLIER 

SECTION 



~ETJ 




V R HI - E R eOf„ o ' 

Vgd) - EjCOJIu, 



C c - COUPLING CAPACITOR 
C e ■ BYPASS CAPACITOR 



PHASE COMPARATOR— High-level reference 
or carrier signal and low-level reference signal 
are applied to multiplier inputs of Exar XR-S200 
PLL IC. K both inputs are same frequency, DC 
output is proportional to phase angle between 
inputs. For low-level inputs, conversion gain is 
proportional to input signal amplitude. For 
high-level inputs (V s above 40 mVRMS), con- 
version gain is constant at about 2 V/rad. — 
"Phase-Locked Loop Data Book," Exar Inte- 
grated Systems, Sunnyvale, CA, 1978, p 9-16. 



0.1 nF 




015V 



INPUT R s 

0-vV\^-«> — j 



OUTPUT 



SUPPRESSING OSCILLATION— Use of positive 
feedback to pin 5 of comparator gives sharp and 
clean output transitions even with slow trian- 
gle-wave inputs, with no possibility of compar- 
ator bursting into oscillation near crossing 
point. Input resistors should not be wirewound. 



♦ 10VREGO 



SIGNAL SOURCE 



Circuit will handle triangle-wave inputs up to 
several hundred kilohertz. — P. Lefferts, Over- 
come Comparator Oscillation Through Use of 
Careful Design, EDN Magazine, May 20, 1978, p 
123-124. 




2/3 CA3600E 



STROBED COMPARATOR— Combination of 
CA3080A opamp and two CMOS transistor 
pairs from CA3600E array gives programmable 
micropower comparator having quiescent 
power drain of about 10 j»W. When comparator 
is strobed on, opamp becomes active and circuit 
draws 420 juW while responding to differential- 
input signal in about 8 /is. Common-mode input 
range is -1 V to +10.5 V. Voltage gain of com- 
parator is typically 130 dB. — "Linear Integrated 
Circuits and MOS/FET's," RCA Solid State Divi- 
sion, Somerville, NJ, 1977, p 279. 



| INPUT 

L_trrrtu^ 




-,.JT 



5.0 V 
-0.5V 



15 TURN BALANCE 



MICROVOLT COMPARATOR— Combination of 
National LM121A preamp and LM111 compar- 
ator serves for comparing DC signal levels that 
are only within microvolts of each other. With 
bias network shown, preamp has open-loop 
temperature-stable voltage gain close to 100. 



-O -10V REG 



Separation of preamp from comparator chip 
minimizes effects of temperature variations. 
Circuit hysteresis is 5 jtV, which under certain 
conditions can be trimmed to 1 /*V. — "Linear 
Applications, Vol. 2," National Semiconductor, 
Santa Clara, CA, 1976, LB-32. 



5-V CLAMPED COMPARATOR— R, and R 2 pro- 
vide +3.8 Vbias for D„ clamping positive output 
of comparator opamp to +5 V. D 2 limits nega- 
tive output swing to -0.5 V. Open-loop circuit 
means that output voltage will vary in propor- 
tion to load current. — W. G. Jung, "IC Op-Amp 
Cookbook," Howard W. Sams, Indianapolis, IN, 
1974, p 226-228. 



COMPARATOR CIRCUITS 



163 



R; < 470 !! 



High=>LL, <V„ <UL, 
Low=>U, > _,„ >L'L, 




High=o LL, < E in < UL, 
Low=>LL : >E,„ >Ul, 



0.** 

^ — High=>LL, <E,„ <UL, 

X Low=>LLj >C„ >UL, 

^E 0s 



* All amplifiers are type 101 or 101A. 
•"All diodes are type 1N91 4. 



STAIRCASE WINDOW COMPARATOR— Cas- 
cading of 101-type window comparators for se- 
quential operation indicates which of three win- 
dows input voltage is in . Input voltage is applied 
in parallel to all comparators. Output goes high 
only for comparator whose range includes volt- 



age value of input. Lamp or other indicator can 
be added to each output line to give visual in- 
dication of voltage range. — W. G. Jung, "IC Op- 
Amp Cookbook," Howard W. Sams, Indianap- 
olis, IN, 1974, p 233-234. 



(Lower limit) 




(Upper Limit) 



INTERNALLY GATED WINDOW COMPARA- 
TOR — Operation is based on fact that source 
and sink currents available at pin 8 of 101 
opamp are unequal, with negative-going drive 
being larger. Voltage at pin 8 is low if either 
comparison input (A, or A 2 ) so dictates. Both A, 
and A 2 must have high outputs for pin 8 to be 
high. Outputs of A and A 2 thus follow pin 8 
since opamps have unity gain. D, and D 2 form 
clamp network. Either output of A, or A 2 can be 
used. Outputs go to +5 V only when input volt- 
age is in window established by upper and 
lower voltage limits. — W. G. Jung, "IC Op-Amp 
Cookbook," Howard W. Sams, Indianapolis, IN, 
1974, p 231-232. 



SIGNAL INPUT 



26-30V 




UPPER LEVEL (-2.1V) 
ADJUSTMENT , E 



1.9-2.1 V WINDOW COMPARATOR— When 
positive input voltage is between levels set by 
R1 and R5, relay is actuated and green indicator 



lamp is turned on. Red lamp is on for voltages 
outside limits of window. Article gives design 
equations and traces operation of circuit. Num- 



ber of components can be greatly reduced by 
changing opamps to LM111 comparators. — J. 
C. Nirschl, 'Window' Comparator Indicates Sys- 
tem Status, EDNIEEE Magazine, June 15, 1971, 
p 49-50. 



164 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



OUTPUT 1 OUTPUT 2 





















f, +v 


11 




o 


o 

1 12 


10 








RIGHT 
CLOCK g 






















a 






C 




D 




RIGHT-LEFT 




R 1 
S 




R 1 
S 






R 1 
S 




-R 1 
- S 


COMMAND 6 










LEFT 
CLOCK 8 








































SN7495 










2 


3 


4 _ 5 






















FREQUENCY/PHASE UP TO 25 MHz— Universal 
shift register such as 5495/7495 is connected to 
compare both frequency and phase of two car- 
rier signals anywhere in range from DC to 25 
MHz. When f, is greater than f 2 , output is 1; 
when f, is less than f 2 , output is 0. For f, = f 2 , 
output is square wave whose duty cycle varies 
linearly with phase difference between f, and f 2 . 
Comparisons are almost instantaneous, requir- 
ing at most two carrier cycles. — J. Breese, Sin- 
gle IC Compares Frequencies and Phase, EDN 
Magazine, Sept. 15, 1972, p 44. 



VARIABLE BIPOLAR CLAMPING— Precision 
comparator provides independent regulation of 
both output voltage limits without connection 
to comparison inputs. A 2 and A 3 are comple- 
mentary precision rectifiers having indepen- 
dent positive and negative reference voltages, 
with both rectifiers operating in closed loop 
through A,. A 2 senses positive peak of E„ and 
maintains it equal to H-V clamc by adjusting volt- 
age applied to D,. A 3 and D 3 perform similar 
function on negative peaks. Feedback network 
around output stage of A regulates output volt- 
age independently of inputs to A,. — W. G. Jung, 
"IC Op-Amp Cookbook," Howard W. Sams, In- 
dianapolis, IN, 1974, p 228-229. 




SIGNAL /NO 




INVERTER ^^_^ 



-I 7545/ V 



MV54! 

& 



LEVEL-CROSSING DISPLAY— Uses Monsanto 
MV5491 dual red/green LED, with 220 ohms in 
upper lead to +5 V supply and 100 ohms in 
lower +5 V lead because red and green LEDs in 
parallel back-to-back have different voltage re- 
quirements. Circuit requires SN75451 driver ICs 
and one section of SN7404 hex inverter, with 
LM311 comparator. All operate from single +5 
V source. Provides indicator change from red to 
green with input change of only a few milli- 
volts. — K. Powell, Novel Indicator Circuit, Ham 
Radio, April 1977, p 60-63. 



FREQUENCY COMPARATOR— Can be used 
with wide range of clock frequencies up to 5.3 
MHz to provide output frequency that is equal 
to absolute difference between input frequen- 
cies f, and f 2 . Article traces operation of circuit 
and gives design equations. — P. B. Morin, Fre- 
quency Comparator Provides Difference Fre- 
quency, EEE Magazine, April 1971, p 65-66. 



KCh 



L 



IC2 
SN5474 



t±T 



c ffi 

CLEAR 



PRESET 

-HD C 

FF2 



L- + - 



IC3 
SN5474 



t-i 



C 
CLEAR 



:£: 



=p 



— Tc~\ 

SN5400 



CLEAR 



■ V 7~™_| [NOT USED j 



jH 



h 



[lC4~ 
■SN5402 I 



pO 4 ^ 



NOTUSED I 




CYCLE-STORING AND SAMPLING CIRCUITS- 



-CONSECUTIVE PULSE DETECTOR CIRCUIT - 



COMPARATOR CIRCUITS 



165 




UUA35J3 
THERMISTOR 



4-BIT BCD COMPARATOR— Provides less than, 
equal to. or greater than comparison between 
setting of BCD thumbwheel switch at X and 
BCD input digit at Y (Y is count preset into 74192 
up/down counter). If equality does not exist, cir- 
cuit will count up or down until it reaches equal- 
ity, and thereby calculate difference between 
BCD values. Separate register can be used to 
store up or down counts required to reach 
equality. — R. A. Scher, Digital Comparator Is 
Self-Adjusting, EDN Magazine, Sept. 1, 1972, p 
51. 




INDEPENDENT SIGNALS— Single AD521 in- 
strumentation amplifier compares two inde- 
pendent signal levels from sources having no 
common reference point. When one differential 
signal is applied to usual input of opamp and 
other to reference input, output is proportional 
to difference. Positive feedback provides small 
amount of hysteresis, to eliminate ambiguity 
and reduce noise susceptibility. Stable thresh- 
old of about 25 mV is derived from AD580 low- 
voltage reference circuit. Reference voltage is 
2.5 V, but values used for R s and R s are in ratio 
of 1:100 so comparator output switches when 
normal input is about Vioo of reference input. 
Output is negative when normal input is zero, 
and switches positive when input exceeds 
threshold. Output swings ±12 V as inputs go 
through critical ratio. R 3 and D, provide TTL- 
compatible second output. — A. P. Brokaw, You 
Can Compare Two Independent Signal Levels 
with Only One IC, EDN Magazine, April 5, 1975, 
p 107-108. 



VOLTAGE COMPARATOR— Motorola MC1539 
opamp provides excellent temperature charac- 
teristics and very high slewing rate for compar- 
ator applications. Zener connected to pin 5 lim- 
its positive-going waveform at output to about 
2 V below zener voltage. Silicon diode con- 
nected to output limits negative excursion of 
output to give protection for logic circuit being 
driven. Parallel RC network in output provides 
impedance matching and minimizes output cur- 
rent overload problems. — E. Renschler, 'The 
MC1539 Operational Amplifier and Its Applica- 
tions," Motorola, Phoenix, AZ, 1974, AN-439, p 
IB. 




+ 10 V 



9.1 k 
-0 V O VW 



INPUT SWEEP 
SIGNAL 

=K 20 KHz 




-15 V 5 k +15 V 




e„>0O 



~7 



>— d 



r )e r 



VOLTAGE-CONTROLLED HYSTERESIS— Pre- 
cise, independent control of comparator trip 
point and hysteresis is achieved by switching 
hysteresis control signal e h to comparator input 
with Q, and Q 2 when opamp changes state. Cir- 
cuit avoids hysteresis feedback error while 
achieving inherent 0.01% trip-point accuracy of 
comparator. Control voltage e, determines first 
trip point. When opamp output is negative, Q : 
is held off and Q 1 is on for connecting nonin- 
verting input to ground. Output switching oc- 
curs when input signal e, drives input of invert- 
ing amplifier to zero. — J. Graeme, Comparator 
Has Precise, Voltage-Controlled Hysteresis, 
EDN Magazine, Aug. 20, 1975, p 78 and 80. 



5pF 



(e = 0, R,-. ~| 



166 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




ZENER REFERENCE— One section of RS3900 
quad opamp is connected as comparator using 
zener D1 for reference voltage. When voltage 
applied to pin 13 by R1 exceeds breakdown volt- 
age of zener D1, comparator amplifies differ- 
ence voltage to produce output voltage high 
enough to turn on LED. Can be used for class- 
room demonstration of comparator action. 
Zener breakdown should be under 9 V. LED can 
be Radio Shack 276-041.— F. M. Mims, "Semi- 
conductor Projects, Vol. 2," Radio Shack, Fort 
Worth, TX, 1976, p 35-42. 




INDEPENDENT HYSTERESIS ADJUSTMENT— 
Trip point and hysteresis of comparator opamp 
A, can be adjusted independently, with trip 
point being determined by setting of R, or pro- 
grammed by DC voltage applied to R 2 . Opamp 
A 2 provides polarity inversion and rectification 
of A output. Hysteresis control R, is in feedback 
path from A 2 back to A,. Amount of hysteresis 
is determined by ratio of R 3 to R s . With values 
shown, circuit output levels are and 5 V. — G. 
Tobey, Comparator with Noninteracting Ad- 
justments, EDNBEE Magazine, Oct. 1, 1971, p 
43. 




FREQUENCY COMPARATOR— Circuit using 
CA3096 transistor array plus one discrete diode 
develops DC output voltage that is proportional 
to difference between frequencies of input sig- 
nals f, and f 2 . Maximum input frequency is 10 
kHz. — "Circuit Ideas for RCA Linear ICs," RCA 
Solid State Division, Somerville, NJ, 1977, p 17. 



SLEW RATE — Circuit measures slew rate of 
input signal with Am685 comparator in circuit 
having delay-line length under 10 ns. When 
slew rate exceeds predetermined limit set by R 6 , 
comparator changes state and latches, turning 
on LED. Pushing reset switch restores normal 
operation. Based on comparison of input signal 
with time-delayed counterpart. Derivative of 
input signal, equal to its instantaneous slew 
rate, is measured accurately for swings of 6 V 
P-P as found in most 50-ohm video signals. Ac- 
tion is fast enough to detect glitches. — R. C. Cul- 
ter, Slew-Rate Limit Detector Is Simple, yet Ver- 
satile, EDN Magazine, Aug. 20. 1977, p 140-141. 



SLEW RATE 
LIMIT 
ADJUST 




INPUT 
BALANCE 



COMPARATOR CIRCUITS 



167 




COMPARATOR DRIVES LAMP— Classroom 
demonstration circuit for comparator action 
uses transistor to amplify output of one section 
of RS339 quad comparator, to boost output cur- 
rent enough for driving 60-mA lamp. Lamp 
comes on when voltage at movable arm of 500K 
pot is greater than half of supply voltage. — F. 
M. Mims, "In tag rated Circuit Projects, Vol. 6," 
Radio Shack, Fort Worth, TX, 1977, p 33-41 . 



STROBED MICROPOWER— Uses CA3080A var- 
iable opamp and CA3600E CMOS transistor 
array. Quiescent power drain from ± 12 V supply 
is only 1 /aW, increasing to 420 ftW when com- 
parator is strobed on to make CA3080A 
active.— "Circuit Ideas for RCA Linear ICs," RCA 
Solid State Division, Somerville, NJ, 1977, p 16. 




INPUT SIGNAL(Es) 
O 




V*-6V 

I 



Qv*=6v 



REGULATOR 

IN 

CA306O 




WHEN UPPER LIMIT 
IS EXCEEDED 



CA3086 




UPPER LIMIT 
FLIP-FLOP 



SATURATES WHEN 
UPPER LIMIT IS 
EXCEEDED 



WHEN INTERMEDIATE 
REFERENCE LIMIT 
IS REACHED 



QV* = 6V 



WHEN LOWER LIMIT 
IS EXCEEDED 



2K 

LOWER LIMIT 

REFERENCE 

VOLTAGE 



NOTE 2- Es>Eu=Q|(ON),Q 2 (0FF) 



E S < U 'Q|(0FF),0 2 (0m 

E s <E L *Q 2 (0N),Q|(0FF) 



CA3086 




LOWER LIMIT 
FLIP-FLOP 



SATURATES WHEN 
LOWER LIMIT IS 
EXCEEDED 



NOTE I : ITEMS IN SHADED AREAS ARE EXTERNAL 

TO THE CA3086 
RESISTANCE VALUES ARE IN OHMS 



THREE-LEVEL COMPARATOR— All three sec- lower limit is exceeded, appropriate output is types of industrial control applications.— "Cir- 

tions of CA3060 three-opamp array are used activated until input signal returns to prese- cuit Ideas for RCA Linear ICs, " RCA Solid State 

with CA3086 transistor arrays to provide three lected intermediate limit. Suitable for many Division, Somerville, NJ, 1977 p 17 
adjustable limits for comparator. If upper or 



168 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



V r . (+5V TYP) 




A, (D. U.T.I: NON-INVERTING COMPARATOR WITH 
10% HYSTERESIS UNDER TEST 
A 7 : VOLTAGE FOLLOWER, LM310 
L, : RELAY, COUCH 2X10B460A 



MEASURING THRESHOLDS— Upper and lower 
thresholds of noninverting comparator under 
test (A,) are read on DVM at end of capacitor 
charge and discharge cycles initiated by S, and 
S 2 . With d discharged, relay L, is energized. 
Closing S, allows C, to charge toward V C c- 
When upper threshold is reached, relay drops 
out and meter is read. Closing S 2 starts dis- 
charge cycle which stops at lower threshold. 
Reverse relay connections when testing invert- 
ing comparator. — E. S. Papanicolaou, Compar- 
ator Is Part of Its Own Measuring System, EDN 
Magazine, Aug. 5, 1974, p 76. 



COMPARATOR DRIVES LED— Simple class- 
room demonstrator of comparator action uses 
one section of RS339 quad comparator. Refer- 
ence voltage applied to positive input of com- 
parator is half of supply voltage. R1 serves as 
voltage divider applying variable voltage to in- 
verting input. When voltage applied to pin 6 by 
R1 exceeds reference voltage on pin 7, compar- 
ator switches on and LED lights. R4 is chosen 
for use with Radio Shack 276-041 red LED. — F. 
M. Mims, "Integrated Circuit Projects, Vol. 6," 
Radio Shack, Fort Worth TX, 1977, p 33-41. 



Bl;k 500 K 
6V-=- 




R2 
100 K 



Q+12V 



v , N o 




WINDOW DETECTOR— Uses one IC regulator to 
compare output voltages of two separate volt- 
age dividers with fixed reference voltage. Re- 
sulting absolute error signal is amplified and 



converted to TTL-compatible logic signal. Volt- 
age divider for lower limit of window detector 
is R,-R 2 and for upper limit is R 3 -R,. Article covers 



circuit operation in detail. — N. Pritchard, Win- 
dow Detector Uses One IC Regulator, EDN Mag- 
azine, May 20, 1973, p 81 and 83. 



COMPARATOR CIRCUITS 



169 




DUAL LIMITS — Opamp used without frequency 
compensation gives positive output only when 
input voltage exceeds 8.5 V in either polarity. 
Resistors in supply leads determine limit points. 
For inverted output, reverse inputs to opamp. 
Diodes are 1N914.— K. Pickard, Dual Limit Com- 
parator Using Single Op-Amp, Wireless World, 
Dec. 1974. p 504. 




VOLTAGE-WINDOW COMPARATOR— Use of 
LM111 opamps minimizes number of compo- 
nents required to turn on green indicator lamp 
when input voltage is between predetermined 
limits set by 2K pots. Similar circuit using 741 
opamps requires total of 31 components. Im- 
proved circuit draws only 120 nA from voltage 
level being monitored, and operates within 
0.3% threshold level stability using single un- 
regulated supply varying ±3 V from 28 V.— D. 
Priebe, Comparators Compared, EDNIEEE Mag- 
azine, Oct. 1, 1971, p 61. 



CHAPTER 15 

Contact Bounce Suppression Circuits 



Used to solve bounce problems of switch and relay contacts during closing or 
opening. 



BOUNCELESS SQUARE OUTPUT— NE555 
timer eliminates need for gates to suppress con- 
tact bounce. Timer can provide pulse at least 5 
ms long (much longer if desired) and can remain 
on as long as trigger input (key pulse) is low 
(grounded). Timer triggers on negative-going 
edge of low-going pulse, such as key down to 
ground. Common negative is isolated from 
ground. V cc can be 5 to 15 VDC. Timer output 
can be connected directly to exciter keying 
input for negative grid keying. Because of 
square-wave output on make or break (100 ns 
each), circuits must be added in exciter or be- 
tween keying transistors to provide at least 
5-ms rise and fall times for Morse or RTTY key- 
ing. — B. Conklin, Improving Transmitter 
Keying, Ham Radio, June 1976, p 44-47. 



^N^ 



Ui 



TT 



HI 

1 °°'T 1 




± 



ARCHER 279-059 



♦15V ' 

Vss 




_r 



15 14 13 12 11 10 3 

MM14511 
4 5 8 7 12 6 



JP 



-J 



DMB863 
6 



40 35 33 32 31 30 29 28 27 23 
1 

MM5865 

13 14 15 






1 t I I 

— i s, l S2 1 



S3 
INPUT 



RESET START 



J. * 1 



± 



SWITCH-CLOSURE COUNTER— National 

MM5865 universal timer and counter chip is 
used with 74C00 debouncer and LM555C timer 
to drive digital display that counts closures of 
manual switch S3. Reset transition restores dis- 
play to 0000. BCD segment outputs of MM5865 
feed LED 4-digit display through MM14511 in- 
terface, while digit enable outputs go to display 
through DM8863 driver.— "MOS/LSI Data- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 2-23-2-32. 



170 



CONTACT BOUNCE SUPPRESSION CIRCUITS 



171 



vcc 



DEBOUNCER — Generates single pulse on 
switch closure, provided wiper of switch 
bounces only between contact and an open. 
Output A goes low when switch is pushed, and 
at same time output B goes high. — E. E. Hriv- 
nak. House Cleaning the Logical Way, 73 Mag- 
azine, Aug. 1974, p 85-90. 



ih ?n.o. 




♦OUTPUT A 



♦OUTPUT B 



IK 2/4 7400 




ICI 

SN7400N 

(TEXAS INST) 

OR 

MOTOROLA 

HEP-C3000 



ONE PULSE PER PUSH— Circuit generates only 
one rectangular pulse for each actuation of 
pushbutton switch, even if contacts bounce. 
TTL gates IC1 are wired as RS flip-flop (latch) 
that triggers mono MVBR IC2 having fixed-du- 
ration positive and negative output pulses. Out- 
put drives are increased by TTL inverting buffer 
gates. — H. Olson, Further Adventures of the 
Bounceless Switch, 73 Magazine, Feb. 1975, p 
111-114. 




6 6 

6 3 4 6 

1 IPs.. < 



0-J 

6 






SN7430 




'ASN74123 



LOGIC 
SYSTEMS 



3 



6 6 




E 



LOW LEVEL 
DEBOUNCE 



HIGH LEVEL 
DEBOUNCE 



POS2 
POS3 
NAND OUT ® ■ 

ONE-SHOT ® • 



-*\ h- 



CONTACT BOUNCE 



(-«— T (0.4 SEC)— >-| 



ROTARY SWITCH DEBOUNCE— Outputs from contact for interval determined by values used 



mono (one-shot) provide common returns for 
rotary switch. Multi-input NAND gate, tied to 
normally high signals from one deck of rotary 
switch, instantly detects opening of one contact 
and triggers mono. Mono then simulates open 



for R 7 and C,; for values shown, delay is 400 
ms. — E. S. Peltzman, Circuit Eliminates Rotary- 
Switch Bounce Problems, EDN Magazine, April 
20, 1978, p 132. 




BOUNCELESS ISOLATOR— Integrating fttterC,- 
R 2 eliminates effects of contact bounce that may 
be superimposed on digital input signal feeding 
optoisolator. Photodiode in optoisolator drives 
Schmitt trigger that makes output to TTL cir- 
cuits change state when LED is turned en fcy 
input signal.— C. E. MrtcheH, Optical Coupler 
and Level Shifter, EDNIEEE Magazine, Feb.1, 
1972, p 55. 



172 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



DEBOUNCING WITH COUNTER— Circuit uses 
CMOS counter/decoder with any inexpensive 
200-Hz or higher clock such as CMOS two-gate 
oscillator or 555 timer. Signal to be denounced 
is fed directly to reset input of counter, with no 
preconditioning. When contact is made by 
switch, counter unclears and starts counting 
up. Each bounce of contact resets counter, so it 
cycles between states and 1 until contacts set- 
tle. Counter then delivers clean nonoverlapping 
pulses to remaining output lines, any of which 
may be used as conditioned output signal. 
When counter reaches state 7, it inhibits itself 
to prevent repeated pulsing of output lines. 
When switch is opened, cycling action is re- 
peated during bounces, with output never 
going higher than state 1. After bouncing, 
counter is held in clear state ready for next clos- 
ing. — L. T. Hauck, Solve Contact Bounce Prob- 
lems Without a One-Shot, EDN Magazine, Sept. 
5, 1975, p 80 and 82. 




OUTPUTS 




ON 



ITPUT 



OUTPUT 



OFF 



'jmcioioJ— 



vW- 



BOUNCELESS MAKE/BREAK— Circuit elim- 
inates switch bounce problems during closing 
as well as opening. When switch is closed, Q 
output of flip-flop goes to logic 1 for delay pe- 
riod determined by RC time constant. Releasing 
switch operates NAND gate, making its output 
go to logic 1. This charges C through R until 
reset level is reached. Flip-flop then resets, 
changing Q output to logic 0. Values for R and 
C are chosen according to bounce duration of 
switch used. Fortypical 1-A SPST switch, 10,000 
ohms and 0.47 juF were used. — L. F. Walsh and 
T. W. Hill, Make-and-Break Bounceless Switch- 
ing, EDNIEEE Magazine, July 15, 1971, p 49. 



MOMENTARY CONTACT 
DPST PUSH-BUTTONS 
14 ea.) 

+5V 2 INPUT NAND 

I GATES 

<\ 2 ea 7400 



I 

+5V 

I 

+5V 

1 



o 



4 INPUT NOR 

GATES 

2ea 7475 



r^ 



f> 



m 



^ 



o 



w 



^ 



o 



m 



<l=i: 



^¥ 



BOUNCE-FREE INTERLOCKING— Arrangement 
provides low-cost equivalent of mechanically 
interlocked switch assembly, while providing 
TTL compatibility and freedom from switch 
bounce. Momentary pressing of any pushbut- 
ton restores its associated RS flip-flop to normal 
and makes output of that channel high. Ar- 
rangement uses cross-coupled two-input 
NAND gates for each flip-flop, connected so 



+Vcc 
'5-15v. 



s* 



\ O00K 

VAJ >1meg %SN74C02 



100K< 
Imeg * 



32: 



each actuation produces an output and resets 
all other flip-flops. If two or more buttons are 
pushed simultaneously, all their channels will 
go high, but only last one released will stay on. 
Any number of channels may be added. — B. 
Brandstedt, Digital Interlocking Switch Is Inex- 
pensive to BuNd, EDN Magazine, Dec. 15, 1972, 
p42. 




LATCHING GATES— SN74C02 quad two-input 
NOR gate forms latching circuit in which first 
noise pulse produced by switch latches circuit, 
making it immune to contact bounce. — I. Math, 
Bounceless Switch, CO, July 1976, p 50. 



CONTACT BOUNCE SUPPRESSION CIRCUITS 



173 



■o 



C V*r-*-i 

IS 



22k 



jtej 



x>- 



DELAYED START— Keyed output of RTTY ter- 
minal equipment or other keys and relays is de- 
layed by 74123 dual mono for at least 5 ms while 
contact bounce settles down. Can be used for 
calculator keyboards, flip-flop testers, and other 
applications in which final clean pulse length is 
not highly important. — B. Conklin, Improving 
Transmitter Keying, Ham Radio, June 1976, p 
44-47. 



KEYBOARD BOUNCE ELIMINATOR— Dual 9602 
mono MVBR is used with Harris HD-0165 key- 
board encoderto generate delayed strobe pulse 
St', with delay set at about 10 ms by first mono. 
Pulse width is determined by second mono and 
should be set to meet system requirements. 
Circuit eliminates effects of arcing or switch 
bounce and provides proper encoding under 
two-key rollover conditions. — "Linear & Data 
Acquisition Products," Harris Semiconductor, 
Melbourne, FL* Vol. 1, 1977, p 6-4. 



DTI OR OPEN 
COLLECTOR 
, GATE 



DUAL M0N0ST ABLE 
T9S02 OR EQUIVALENTl. 

2/JF .' 

2 . m 



-frr i 





^0 01 uf 



■O OUTPUT 



GATES FORM SWITCH— Each time pushbutton 
switch is closed momentarily, voltage on C, 
makes inverter A change state, with positive 
feedback from inverter B, to give alternate ON 
and OFF action. R, delays charging and dis- 
charging of C,, making circuit essentially im- 
mune to contact bounce. Switch works equally 
well with either CMOS or TTL gates. Values of 
R, and C, are not critical. — T. Tyler, Inverters 
Provide "ON-OFF" from Momentary Switch, 
BDN Magazine, June 20, 1976, p 126. 



CHAPTER 16 

Converter Circuits — Analog-to-Digital 



Includes circuits for converting DC, audio, and video analog inputs to linearly 
related binary, BCD, or Gray-code digital outputs. Some circuits have 
autoranging or some type of input compression, input multiplexing, and input 
buffering. 



TRANSMIT INPUT 

±5 V ANALOG IN 

P 



SEND/RECEIVE 
COMMAND 
HIGH* SEND 
LOW ■ RECEIVE 



GROUND FOR 
NON- 

DIFFERENTIAL 
INPUTS 




+ 5V 



CL 
1/2 c 
7474 

PR 



p 



10 



START 



2 



TIME SHARED 
, BI-DIRECTIONAL 
-O SERIAL DATA 
" BUS 



1 



S V+ GND 

SUCCESSIVE 

APPROXIMATION 

REGISTER 

AM2502 
(SAR) 



CC 



MSB 



)+5V 



DIFFERENTIALS- 
ANALOG °~ 
CURRENT _ 
OUTPUT O^ 

RECEIVE OUTPUT 




-Oendofconv. 



REF-OI 
+ 10V 



E/D SB B1 B2 B3 B4 85 B6 B7 



DAC-76 



V+ 



VREF<+> 

vref(-) 

Vlc 



,3 o ,8 o % 



-I5V +15V 



SERIAL DATA OUTPUT— Precision Monolithics 
ICs form transceh/ing converter suitable for use 
in control systems incorporating 8-bit micro- 
processors. Output conforms with Bell-System 
p-255 logarithmic law for PCM transmission. 



Applications include servocontrols, stress and 
vibration analysis, digital recording, and speech 
synthesis. Start must be held low for one clock 
cycle to begin send or receive cycle. Conversion 
is completed in nine clock cycles, and output is 



available for one full clock cycle. Other half of 
system is identical. — "COMDAC Companding 
D/A Converter," Precision Monolithics, Santa 
Clara, CA, 1977, DAC-76, p 12. 



174 



CONVERTER CIRCUITS— ANALOG-TO-DIGITAL 



175 



10M Si 
INPUT O Wr 



♦ TO A/D INPUT 




SELF-CONTROLLED AUTORANGING— DG201 
quad analog switch inserts one of four atten- 
uator resistors in input circuit of Siliconix LD130 
or comparable A/D converter under control of 
autoranging pulse output derived from con- 
verter. Control logic includes 74C00 quad two- 
input NAND gate with two sections connected 
as flip-flop, 74C95 4-bit right-shift left-shift reg- 
ister, and 74C20 dual four-input NAND gate. — 
"Analog Switches and Their Applications," Sil- 
iconix, Santa Clara, CA, 1976, p 6-28-6-29. 



INTERFACE TO A/D 



AUTORANGE LOGIC PULSE INPUTS 




SOFTWARE CONTROL— Innovative software 
for Intel 8080A microprocessor eliminates need 
for peripheral isolation devices when using Pre- 
cision Monolrthics DAC-08E D/A converter and 
CMP-01C comparator for 8-bit A/D conversion. 



Technique can easily be expanded to 10-bit or 
12-bit conversions and adapted to other micro- 
processors. Logic of microprocessor replaces 
conventional successive-approximation regis- 
ter. 8 lowest-order address bits control data bit 



input to DAC, using software given in article. — 
W. Rrtmanich and W. Freeman, "Software Con- 
trolled Analog to Digital Conversion Using DAC- 
08 and the 8080A Microprocessor," Precision 
Monolithics, Santa Clara, CA, 1977, AN-22, p 3. 



176 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



INPUT 
Q 




DIGITAL 

DATA 

OUTPUT 



100 MHz 
CLOCK INPUT 



10-BIT ACCURACY— Single-slope A/D converter 
gives high-speed conversion of DC input volt- 
age to digital data output. For 0-10 V input, 
1024 pulses of 100-MHz clock appear at full scale 
and 512 at half scale. When command pulse is 
applied, 2N914 transistor resets 1000-pF capac- 
itor (820 and 180 in parallel) to V. Capacitor 
begins to charge linearly on falling edge of com- 
mand pulse, to 2.5 V. 10-/us ramp is applied to 
AMD686 for comparison with unknown volt- 
age. Output of opamp is pulse whose width is 
proportional to input voltage and can therefore 
be used to gate 100-MHz clock. — J. Williams, 
Low-Cost, Linear A/D Conversion Uses Single- 
Slope Techniques, EDN Magazine, Aug. 5, 1978, 
p 101-104. 



CONVERT COMMAND 

(30 nSEC MIN) 



VIDEO COMPRESSOR— Nonlinear function am- 
plifier IC-2 compresses video input signals as 
required to compensate for inefficient quanti- 
zation where there are too many levels for small 
signals and too few levels for large signals. De- 
signed to feed 6-brt analog-to-digital converter, 
IC-1 attenuates input -20 dB and shifts level. 
Output of IC-2 is amplified by IC-3 to voltage 
range comparable to that of input signal. IC-4 
acts as temperature compensator and output 
level shifter. R 7 nulls small output offsets. — J. 
B. Frost, Non-Linear Function Amplifier, EEE 
Magazine, March 1971, p 78. 



TO QUANTIZER 
(A-0) 




IC-1, 3,8,4 RADIATION RA25ZO 
IC-2 TI SNS6502 

D-l HP IN5I65 

ALL RESISTORS *l% 
UNLESS NOTED ° " 



BIPOLAR 
REFERENCE 
INPU TQF RE Q'O) ANAL0G 
INPUT 




/77_L°'/<< 



I .OI/4f t~ **' 

_L.5oV JT i^f 

-p 35V 






ANALOG 
GROUND 



CONVERSION 
COMPLETE 
CLOCK 
INPUT 



T Tf 



POWER 
GROUND 



8-BIT SUCCESSIVE APPROXIMATION— Uses 
Precision Monolithics DAC-100 CCQ3 D/A con- 
verter and CMP-01CJ fast precision comparator 
in combination with Advanced Micro Devices 
AM2502PC or equivalent successive approxi- 
mation register to compare analog input with 
series of trial conversions. Clamp diodes mini- 
mize settling time and prevent large inputs 
from damaging DAC output. Digital output is 
available in serial nonretum-to-zero format at 
data output DO shortly after each positive- 
going clock transition. — D. Soderquist, "A Low 
Cost, Easy-to-Build Successive Approximation 
Analog-to-Digital Converter," Precision Mono- 
lithics, Santa Clara, CA, 1976, AN-11, p 3. 



CONVERTER CIRCUITS— ANALOG-TO -DIGITAL 



177 



-15V + I5V 

9 




4-ps CONVERSION TIME— Provides conversion 
of analog input to 8-bit digital output by suc- 
cessive approximation, with conversion time of 
4 (is. Advanced Micro Devices AM2502 succes- 
sive-approximation register contains logic for 
Precision Monolithics DAC-08E and CMP-01C 
comparator. — D. Soderquist and J. Schoeff, 
"Low Cost, High Speed Analog-to-Digrtal Con- 
version with the DAC-08," Precision Monolith- 
ics, Santa Clara, CA, 1977, AN-16, p 3. 



CONVERSION 
COMPLETE 

TTL CLOCK INPUT O 
2.25 MHZ 



CONNECT "START" TO "CONVERSION 
COMPLETE" FOR CONTINUOUS CON- 
VERSIONS. 



V|N O 



TO INPUT OF A/D 
(200 mV RANGE) 




INTERFACE FROM A/D 

AUTORANGING— Digitally controlled attenua- 
tor uses DG201 quad analog switch as input lad- 
der attenuator switches for A/D converter. 
Switches are controlled by digital logic that de- 



AUTORANGE LOGIC PULSE INPUTS 



tects overrange and underrange information 
from A/D converter and closes appropriate at- 
tenuator path. Circuit is suitable for Siliconix 



LD110/111 or LD111/114 A/D converter.— "Ana- 
log Switches and Their Applications," Siliconix, 
Santa Clara, CA, 1976, p 6-28. 



178 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 10V 
REFERENCE 



ANALOG 
INPUT 

TO +10V 




SERIAL 
OUTPUT 



CONVERSION 
COMPLETE O- 

TTL CLOCK INPUT O- 
2.25MHz 



0-10 V ANALOG INPUT— Used to provide dig- 
ital input to computer for processing and stor- 
age of analog signals. Requires only three ICs in 
addition to external +10 V reference and 2.25- 
MHz TTL clock. Successive-approximation reg- 
ister (SAR) can be Motorola MC1408 or equiv- 
alent. For continuous conversions, connect pins 
10 and 2 of SAR.— "Signetics Analog Data Man- 
ual," Signetics, Sunnyvale, CA, 1977, p 677-685. 



HIGH-IMPEDANCE BUFFER— Two sections of 
Motorola MC3403 quad opamp serve as voltage 
followers for differential inputs of third section 
connected as buffer for MC1505 AID converter. 
Dual transistor Q1, connected as dual diode, 
provides 0.6- V offset at inputs of voltage follow- 
ers, to obtain temperature tracking and pre- 
dictable performance at low bias currents of 
opamp.— D. Aldridge and S. Kelley, "Input 
Buffer Circuits for the MC1505 Dual Ramp A-to- 
D Converter Subsystem," Motorola, Phoenix, 
AZ, 1976, EB-24A. 



47 kJ2 V CC 

r^ ni3T 16 




7 3^C| 

»- Comparator 

"*Ramp Control 

» Zero Adjust 



CR1 



ri; 3 


10 k 0.1% 


R2, 4, 5, 6 


20 kO.1% 


R7, 8 


10 k Pot 


R9 


3.9 k 


R10, 12 


1.2 k 


R11 


10 k 


OA1, 2 


MC1456C 


CR1 


MSD6100 


CR2 


MSD6150 


CR3, 4 


1N914 


Q1 


MPS6415 


CI. 2 


0.1 


LED 


MLED630 



CYCLIC CONVERTER— Unknown voltage is 
successively compared to reference voltage for 
determining each digital bit. After determining 
bit, voltage difference between unknown and 
reference is operated on, then sent to succes- 
sive stages to determine less significant bit. Re- 




-ov f 



+ 15 V 



'R10 



▲ <R12 
X ? O O 6 O 



n 



LED 



t_J L 



suiting digital output is in Gray-code form. Eight 
identical circuits are operated in cascade to pro- 
vide 8-bit A/D converter having accuracy within 
1 LSB and full-scale.range of 0-8 V. Circuit re- 
quires only two MC1456CG opamps per stage, 
with MPS6514 transistor as comparator. 



MSB 



All Others 



Switching diode CR1 is MSD6100, and CR2 is 
MSD6150. Other dioodes are 1N914.— J. 
Barnes, "Analog-to-Digrtal Cyclic Converter," 
Motorola, Phoenix, AZ, 1974, AN-557, p 7. 



CONVERTER CIRCUITS— ANALOG-TO-DIGITAL 



179 



DIFFERENTIAL OPAMP AS BUFFER— Section of 
Motorola MC3403 quad opamp, operating from 
single supply, serves as low-cost unity-gain 
buffer for MC1505 dual-ramp A/D converter, 
Opamp is used as differential amplifier refer- 
enced to MC1505 reference voltage of 1 .25 V. — 
D. Aldridge and S. Kelley, "Input Buffer Circuits 
for the MCI 505 Dual Ramp A-to-D Converter 
Subsystem," Motorola, Phoenix, AZ, 1976, EB- 
24A. 



100 k 



47 k£2 Vcc 

P" Hi3 Tie 




Comparator 
Ramp Control 



+15 V 



MLM301A 

6 v 




MPS6513 



FET-INPUT BUFFER— Used ahead of Motorola 
MCI 505 A/D converter to provide input imped- 
ance of 10 megohms. FETs are connected as dif- 
ferential amplifier having common source leads 
returned to constant-current generator built 
from bipolar transistor, with similar transistor 
providing temperature compensation. Temper- 
ature drift of amplifier is well under 1 mV from 
to 50°C— D. Aldridge and S. Kelley, "Input 
Buffer Circuits for the MC1505 Dual Ramp A-to- 
D Converter Subsystem," Motorola, Phoenix, 
AZ, 1976, EB-24A. 



_ 15 v 6 100 kn 



|""ADDED 
CIRCUIT 




DIGITAL OUTPUT 



TRACKING A/D CONVERTER— Addition of one 
gate to tracking or servo-type A/D converter, as 
shown in dashed box, overcomes instability 
problems otherwise occurring when input volt- 
ages are less than zero or greater than full scale. 



With 8-bit converter shown, count of11111111 
when counting up makes carry output and load 
inputs go low, holding counter in this state so 
subsequent up clocks are ignored. When count 
is all 0s, borrow output goes low and clear input 



goes high, so counter is free to count up only. — 
A. Helfrick, Tracking A/D Converters Need An- 
other Look, EDN Magazine, June 20, 1975, p 118 
and 120. 



180 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




66666666 

DIGITAL 
OUTPUT 



DIFFERENTIAL CONVERSION— Uses high cur- 
rent output capability of Precision Monolithics 
DAC-08 D/A converter and high common-mode 
voltage rejection of CMP-01 comparator to give 
differential-input ADC without input signal con- 
ditioning. Successive-approximation conver- 
sion logic is obtained with REF-01 +10 V refer- 
ence and 2502-type successive-approximation 
register, driven by DAC and comparator. Analog 
input is converted in less than 2 fis. Differential 
input range is 5 V. Diodes are 1N4148. — J. 
Schoeff and D. Soderquist, "Differential and 
Multiplying Digital to Analog Converter Appli- 
cations," Precision Monolithics, Santa Clara, 
CA, 1976, AN-19, p 5. 



REPETITIVE-MODE OPERATION— Quicker con- 
version is obtained in Teledyne Philbrick 4109 
or 4111 A/D converter by restarting converter 
within a few microseconds after status signal, 
using sure-start circuit shown. Reset pulse is 
fed to converter when status signal is held at 
low DC level. When status command is high, 
oscillator A-B is disabled. If reset pulse is not 
obeyed and status signal remains low, oscilla- 
tor starts up until conversion does occur. — R. 
W. Jacobs, "Repetitive Mode Operation for 
Models 4109/4111 Integrating A/D Converters," 
Teledyne Philbrick, Dedham, MA, 1977, AN-28. 



1N914 or 1N4148 OR ANY SILICON SMALL-SIGNAL DIODE 



V 



+o- 

INPUT V x 



-o- 




X" 




5KS2< 



r 



B1 

+ 



DAC-08 



P 6 6 6 6 6 6 o ; 

DIGITAL , , ^ ^x 
OUTPUT ' ' V y 



FOUR-QUADRANT RATIOMETRIC— Uses Pre- 
cision Monolithics DAC-08 D/A converters and 
CMP-01 comparator to drive successive-ap- 
proximation conversion logic using REF-01 +10 
V reference and 2502-type successive-approxi- 
mation register. Imputs V x are connected con- 



ventionally, and inputs V y are connected in mul- 
tiplying fashion. l REf for both DACs is modulated 
between 1 and 3 mA. Resulting output currents 
are differentially transformed into voltages by 
5K resistors at comparator inputs and com- 
pared with V* differential input. When conver- 



sion process is complete (comparator inputs 
differentially nulled to less than % LSB), digital 
output corresponds to quotient V X /V Y . Diodes 
are 1N4148. — J. Schoeff and D. Soderquist, 
"Differential and Multiplying Digital to Analog 
Converter Applications," Precision Monolithics, 
Santa Clara, CA, 1976, AN-19, p 5. 



CONVERTER CIRCUITS — ANALOG-TO-DIGITAL 



181 



8-Bit Data Output 



-o +15V 

Timing Diagram 




0.01 /iF 



BINARY OUTPUT— Converts analog signal in 
range of 0-10 V to 8-bit binary word having all 
OsforOVandall Is for full-scale input of +9.960 
V. Output is 15-V CMOS-compatible but can be 
adapted for TTL compatibility. Maximum con- 



version time is about 26 ms. A 2 and A3 form neg- voltage equals input voltage, comparator out- 

ative-going staircase generator for which start- put goes positive and resets control flip-flop to 

conversion signal is formed by one section of complete conversion.— W. G. Jung, "IC Timer 

556. Opamp A, compares negative output of Cookbook," Howard W. Sams, Indianapolis, IN, 

7530 with input voltage V in . When 7530 output 1977, p 226-228. 



■J BIT PARALLEL DIGIT SERIAL MUX 
S. 



O INPUTS 

-^ ^3 DIGIT SE LECT 1 

r— * Tn All i ncc 



O TO ALL DISPLAY BCD 




FOUR-CHANNEL INPUT MULTIPLEXING— Con- central multiplexer. System is much more eco- 100 kHz and 1 MHz. At 500 kHz, each conversion 
version process is divided between central sta- nomical than having separate AID converter at takes about 15 ms.— S. Kelley, "Analog Data 
tion and remote locations having analog sen- each sensor. Can be extended to 32 channels. Acquisition Network for Digital Processing 
sors. Each station transmits two noise-immune Multiplexing is performed under control of Using the MC1405-MC14435 AID System," Mo- 
low-frequency digital signals under control of clock in Motorola MC14435, operating between torola. Phoenix, AZ, 1975, EB-58. 



182 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



0.01 tlF 




>4>HI- 



1000 pF 



>3. 



R = 200 KS2 for 4111 
-400 KS2 for 4109 



NOTES: A1 - Philbrick 1319 or equivalent 



-t>" 



1/6 SN7404 or equivalent 



TO 
4109/4111 
RESET INPUT 



EXTERNAL TRIGGER— Generates pulse with 
100-ns minimum width in range of 125-250 Hz 
for application to reset input of Teledyne Phil- 
brick A/D converter in applications requiring un- 
attended operation with continuous conver- 
sion. Adjust 100K pot to give 125 Hz for 4109 or 
250 Hz for 4111. Successive stages of SN7404 
inverter provide required sharpening of pulse. 
A1 is positive-starting MVBR. — R. W. Jacobs, 
"Repetitive Mode Operation for Models 41091 
4111 Integrating A/D Converters," Teledyne 
Philbrick, Dedham, MA, 1977, AN-28. 



MOSFET-INPUT BUFFER— Uses Motorola 
MC14007 dual complementary pair plus in- 
verter, with two of MOSFETs connected as dif- 
ferential amplifier for buffering opamp and third 
serving as current source for differential ampli- 
fier. Arrangement gives high input impedance 
required in some applications of MC1505 A/D 
converter for which buffer wes designed. 1- 
megohm pot controls gate voltage for current 
source. Temperature drift is well under 2 mV 
over range of 0-50°C. Pin 14 of MCI 4007 should 
be tied to +5 V.— D. Aldridge and S. Kelley, 
"Input Buffer Circuits for the MC1505 Dual 
Ramp A-to-D Converter Subsystem," Motorola, 
Phoenix, AZ, 1976, EB-24A. 




390pF 




CONVERSION 



FREE RUN 
TRIGGERED INPUT 



NOM CLOCK IOOKHi-ZMHi SET FOR APPROX 900KH2 



VOICE DIGITIZER — Uses 8-bit ADC capable of puter memory for later conversion back to an- +12 V, and pin 4 is -6 V. For IC6 and IC7, pin 14 

sampling AF input signal 1 00,000 times per sec- alog form for such applications as synthesis of is +5 V and pin 7 is ground. 8080 assembler pro- 

ond when using 900-kHz clock. 100-kHz clock speech from phonemes and providing voice an- grams are given for input and output of mem- 

gives9000samplespersecond,aboutminimum swersto queries. Requires about 10,000 bytes ory. — S.Ciarcia, Talk to Mel Adda Voice to Your 

for human voice. Digital output is stored in com- in memory for 1 s of voice data. Pin 7 of IC4 is Computer for $35, BYTE, June 1978, p 142-151. 



CONVERTER CIRCUITS — ANALOG-TO-DIGITAL 



183 



0.1b F 



INITIATE 
CONVERSION 



_TL 



"IN 

1MS2' 



I C INT 

— ■— RJt nF 



IMS!" -1 ■" 

v, N o— VW 1 — 



i IN « iomA f.s. 



270pFI 



£?& 



V D D 




BCD OUTPUTS 



-O A } THOUSANDS 



:s) 
:ij 

A J 

'A J 



23 DATAVALID^ 



HUNDREDS 



BCD OUTPUT— Latched nonmuKplexed paral- 
lel BCD outputs from Teledyne 87S0 3 1 A-digit 
CMOS analog-to-digital converter are suitable 
for liquid crystal and gas-discharge displays. 2- 
mA drain on ±5 V supply permits battery op- 



eration. Features include high linearity, noise termining digital equivalent by counting these 

immunity, and 3Vdigit resolution within pulses. Values shown are for full-scale voltage 

0.025% error. Circuit is based on switching inputof 10V and voltage reference of -6.4V. — 

number of current pulses needed to bring ana- CMOS A-D Converter Provides BCD Output, 

log current to zero at input of opamp, then de- Computer Design, Nov. 1977, p 156 and 158. 




Clock 
3.0 MS < T « 500 MS 



QO Q1 Q2 Q3 Q4 Q5 Q6 Q7 
D SO 

MC14559B 

C EDC 

V DD FF V ss SC 



(A) = 

R1 R2 

(B) 0.5 mA < l ref < 4.0 mA 



O 
+ 12 V 



^ 



Free Run Mode 



S1 Triggered Mode 



O-6.0 V 



Output 



. Serial 
Output (SO) 



-f — o 



Conversion (EOC) 



_q External 
Trigger 



HIGH-SPEED SUCCESSIVE-APPROXIMA- output is used for transmission to one or more proximation A/D Conversion," Motorola, Phoe- 

TION — Total conversion time for 8-bit system other locations. — T. Henry, "Successive Ap- nix, AZ, 1974, AN-716, p 5. 
is about 4.5 j&s. Clock rate is up to 2 MHz. Serial 



184 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



2-DIGIT BCD— Uses Motorola MC14549 succes- 
sive-approximation register and MC1408L-8 D/ 
A converter to give full-scale value of 0.99 V in 
10-mV increments. Input is buffered by opamp 
A1 connected as voltage follower, with pot PI 
set to give output current proportional to un- 
known input voltage. This current is compared 
to that required by total BCD AID converter. Pins 
1-4 and 12-15 of MC14549 provide required 2- 
digit parallel BCD output. Clock frequency can 
be 100 kHz.— D. Aldridge, "Successive Approx- 
imation BCD AID Converter," Motorola, Phoe- 
nix, AZ, 1975, EB-51. 



Gl - G4 - CMOS Inverters 
(MC14001, 14011, 14069 or 
14572) 

A1 - A3 MLM301A (31 




Continuous Conversion 

Triggered 
Conversion (_r) 




• f 1 +5.0 V 

15 |1 |2 | 13 



A1 A2 A3 A4 A5 A6 A7 A8 



Clock 
T «! 2.0 (is 



15 



14 



13 



12 



Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 

D SO 

MC14559B 

C EDC 

Vqd FF V ss sc 



R1 R2 

(B) 0.5 mA < l ref < 4.0 mA 



1 



6 

+ 5.0 V 



500 pF 



^ 



Free Run Mode 



21 Triggered Mode 



-O "15 V 



. Serial 
'Output 



_q External 
Trigger 



8-BIT SUCCESSIVE-APPROXIMATION— Re- MC1408. If output is greater, bit is reset or 

quires only four ICs. For each cycle, most sig- turned off. Process is repeated for next most overall operational figure is about 2 /is per bit 
nificant bit is enabled first, with comparator giv- significant bit until all bits have been tried, com- for 8-bit system. — T. Henry, "Successive Ap- 
ing output signifying that input signal is greater pleting conversion cycle. Conversion time is 18 proximation A/D Conversion," Motorola, Phoe- 
or less in amplitude than output of Motorola /us, total propagation delay is about 1.5 its. and nix, AZ, 1974, AN-716, p 4. 



CONVERTER CIRCUITS — ANALOG-TO-DIGITAL 



185 



O SERIAL DATA OUT 



COMPRESSING A/D CONVERSION— Step size 
increases as output changes from zero scale to 
full scale, in contrast to conventional linear con- 
verter in which step size is constant percentage 
of full scale. Uses Precision Monolithics DAC-76 
D/A converter in combination with CMP-01 
comparator, any standard EXCLUSIVE-ORgate, 
and successive-approximation register for con- 
version logic. Encoding sequence begins with 
sign-bit comparison and decision. Bits are con- 
verted with successive-removal technique, 
starting with decision at code Oil 1111 and 
turning off bits sequentially until all decisions 
have been made. Conversion is completed in 
nine clock cycles. — "COMDAC Companding 
D/A Converter," Precision Monolithics, Santa 
Clara, CA, 1977, DAC-76, p 12. 




CMOS-COMPATIBLE SUCCESSIVE-APPROXI- 
MATION — Converts analog input to 8-bit digital 
output by using MC14559 CMOS successive-ap- 
proximation register with Precision Monolithics 
DAC-100 D/A converter and CMP-01 compara- 
tor. Conversion sequence is initiated by apply- 
ing positive pulse, with width greater than one 
clock cycle, to START CONVERSION input. An- 
alog input is then compared successively to 1 A 
scale, 1 /> scale, and remaining binarily decreas- 
ing bit weights until it has been resolved within 
'A LSB. END OF CONVERSION then changes to 
logic 1 and parallel answer is present in nega- 
tive-true binary-coded format at register out- 
puts. — D. Soderquist, "Interfacing Precision 
Monolithics Digital-to-Analog Converters with 
CMOS Logic," Precision Monolithics, Santa 
Clara, CA, 1975, AN-14, p 4. 



END OF 
CONVERSION 



NEGATIVE-TRUE 
LOGIC OUTPUTS 



rh 



V, N » TO +IOV 
ANALOG- R IN s4ek " 



MAXIMUM FULL SCALE 
SINE WAVE INPUT 
IS 4000HI 





MAXIMUM CLOCK RATE '3.0MHz 



_0<-5V TRACK 
HOLD 



DAC-100CCO3 
10 BIT D/A CONVERTER 



FULL SCALE ADJ. 



IS 2 

2000. 



*1 



DIGITAL 
OUTPUT 



IN 

I 



8-BIT TRACKING — Uses Precision Monolithics 
DAC-100 CCQ3 D/A converter and CMP-01 CJ 
fast precision comparator to make digital data 
continuously available at output while tracking 
analog input. Diode clamps hold DAC output 



t15 9 
_L.02 

-15J 



r 5 



■15 P 



near zero despite input and turn-on transients. 
Unused least significant digital inputs of 10-bit 
DAC are turned off by connecting to +5 V as 
shown. Simple clock circuit shown in dashed 
box is stable over wide range of temperatures 



J, 



1 



POWER 
GROUND 



rl 



ANALOG 
GROUND 



and supply voltages. D/A converter is used in 
feedback configuration to obtain A/D opera- 
tion. — "A Low Cost, High-Performance Track- 
ing A/D Converter," Precision Monolithics, 
Santa Clara, CA, 1977, AN-6, p 2. 



186 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




SINGLE SUPPLY 
FOR OP- AMP 



REMOTE STATION— Multiplexing of large num- 
ber of analog voltages from widely separated 
locations in large industrial control systems is 
simplified by transmitting two noise-immune 
low-frequency digital signals from each remote 
to central multiplexer driving display and mi- 
croprocessor. Central station using MC14435 
controls direction of integration in each remote- 
station MC1405 through ramp control output. 
At beginning of conversion, integrator of 
MC1405 integrates upward for 1000 counts of 
central-station clock. Integrator then ramps 
down while comparator remains high, with 
clock continuing until comparator threshold is 
again crossed. Counts during down ramp are 
latched by counter when comparator goes low, 
and circuits are reset for next conversion. Ana- 
log input voltage is thus transmitted to central- 
station MC14435 as two digital signals.— S. Kel- 
ley, "Analog Data Acquisition Network for 
Digital Processing Using the MC1405-MC14435 
A/D System," Motorola, Phoenix, AZ, 1975, EB- 
58. 



°1 AMP ANALOG. 
INPUT C 



COMPARATOR 



8-BIT .DIGITAL OUTPUT— Digital output is ob- 
tained in parallel format from binary-counter 
output of Exar XR-2240 programmable timer/ 
counter. Recycle time is about 6 ms. Supply 
voltage can be 4-15 V. — "Timer Data Book," 
Exar Integrated Systems, Sunnyvale, CA, 1978, 
p 11-18. 



2R 4R 8R 16R 32R 64R 



3 

o 



LSB 
O— 




=:5oopf 




6 



Vee 



FILTERED BUFFER— Used with Motorola 
MCI 505 A/D converter when making precise 
measurements of slowly varying DC voltages in 
digital voltmeters or in feedback controls. 
Closed-loop front-end buffer provides high 
input impedance and reduces stray noise and 



60-Hz pickup. Two-pole filter is included in 
unity-feedback loop of buffer. Front-end scaling 
circuit is included with buffer. — D. Aldridge and 
S. Kelley, "Input Buffer Circuits for the MC1505 
Dual Ramp A-to-D Converter Subsystem," Mo- 
torola, Phoenix, AZ, 1976, EB-24A. 



CONVERTER CIRCUITS— ANALOG-TO-DIGITAL 



187 





4.99k 
-vW<— 



T 



4-BIT CLOCKLESS— Simple and low-cost ar- wave signals well up into audio range. Even easily cascaded.— B. P. Vandenberg, Tracking- 
rangement of seven CA3130opamps gives con- with relatively slow 741 opamps, signals up to Type A/D Requires No Clock Oscillator, EDN 
version times fast enough for tracking sine- 300 Hz were easily tracked. Additional bits are Magazine, Jan. 20, 1977, p 92 and 94. 



CHAPTER 17 

Converter Circuits — DC to DC 



Use inverters typically operating from DC supplies in range of 2-15 V to 
generate AC voltage at frequency typically in range of 16-25 kHz, for step-up 
by voltage-doubling rectifier or transformer-rectifier combination to give 
desired new positive or negative DC supply voltage that can be as high as 10 
kV. 



+12VO- 




D, 
1N914 



L, 

33mH. 9« 
(0.20 @1kHz) 



:c 2 

10uF 
15V 



-Q-12V 



D 2 
J 1N4742 



+12 V TO -12 V — Transformerless inverting 
DC-to-DC converter has above 55% efficiency 
and can withstand output shorts lasting up to 
several minutes. UJTQ, and base-emitter diode 
of transistor Q 2 form free-running MVBR whose 
25-kHz output is amplified by Qj to drive switch- 
ing-mode converter Qj-L^D,-^. Zener D 2 regu- 
lates output for variations in input voltage or 
output loads up to 40 mA. — G. Bank, Trans- 
formerless Converter Supplies Inverted Output, 
EDN IEEE Magazine, July 1, 1971, p 48. 



+10 TO 18V DC IN 



100/jF/25V 



COMMON > 




*- COMMON 



+ 12 V TO - 12 V— Transforms unregulated +12 
VDC to current-limited regulated -12 VDC. 
Front end of 555 is connected in astable config- 
uration, with R 2 selected to give about 25 kHz 
at pin 3. Control of modulation input to pin 5 



gives voltage regulation and current limiting. 
Circuit tolerates continuous operation under 
short-circuit conditions. With 10-V nominal out- 
put, line regulation is within ±0.05% for input 
and output voltage ranges of 0.3 to 10 V. Load 



regulation is 0.2% for loads from 10 pA to 10 
mA when load impedance is 10 ohms. — R. Dow, 
Build a Short-Circuit-Proof +12V Inverter with 
One IC, EDN Magazine, Sept. 5, 1977, p 177- 
178. 



188 



CONVERTER CIRCUITS — DC TO DC 



189 



-•-+150V 



2N6211 (MOTOROLA) 



jr-ru 1 



EXTERNAL SYNC 
CIRCUIT 

+2V _ 
' I 

2 »/sec 220 

COINCIDENT WITH 
THE LEADING EDGE 
OF HORIZONTAL 
DRIVE PULSE 




150 



°3 

2N3643 



SHORT-CIRCUIT 
PROTECTION 



2.2 mH 



T,- FERROXCUBE TOROID266CT 125 3D3 
T„- FERROXCUBE POT CORE 36 22P - A600-3B7 



2 V TO 20 AND 150 V— Use of 7-turn toroidal 
transformer in self-excited ringing-choke block- 
ing-oscillator circuit improves efficiency of con- 
verter circuit by providing fast switching time. 
Circuit is practical only when input and output 



voltages differ significantly. Blocking oscillator of horizontal drive pulse. This ensures comple- 

is formed by Q„ T 2 , C,, R 2 , and base-bias net- tion of cycle within blanking interval. — N. Tka- 

work FVQ2. Q4 makes possible external syn- cenko. Transformer Increases DC-DC Converter 

chronization, permitting use in television sys- Efficiency to 80%, EDN Magazine, May 5, 1976, 

terns for triggering regulator with leading edge p 110 and 112. 



+6VDC O f 



REMOTE SHUTDOWN 




ALL RESISTOR VALUES IN OHMS 



•SHAFER MAGNETICS 
COVINA, CALIF. 
1213)331-3115 



+6VTO ±15V — Combination of 655 timer and erates as oscillator driving step-up transformer alog Data Manual," Signetics, Sunnyvale, CA, 
two NE550A precision adjustable regulators which feeds full-wave rectifier.— "Signetics An- 1977, p 726-727. 
gives 0.1% line and load regulation. Timer op- 



190 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



500k S0.005S 500k 
I'f 



!*£>££>;; 



V S: 

:3>i 



+12V 

4 







12 V TO - 1 1 V WITH CMOS IC— Bipolar inverter 
and rectifier together provide -11V from 12-V 
auto battery for operating high-threshold MOS 
logic of portable or automotive equipment. 
Diode types are not critical. Inverter draws only 
about 1 mA from 12-V battery on standby and 
supplies 2 mA from -11V terminal.— B. Fette, 
Inexpensive Inverters Generate V ss for Portable 
MOS Applications, EDNIEEE Magazine, Dec. 15, 
1971, p 51. 



BATTERY-LIFE EXTENDER— Conserves battery 
life by charging capacitor from V at efficiencies 
over 80% and by allowing battery to be used to 
lower endpoint voltage. Will generate voltages 
above or below battery voltages. When used in 
capacitor-discharge ignition system, power 
conversion efficiency is so high that heatsink is 
unnecessary and only one power transistor is 
needed. Gives full output voltage even when car 
battery voltage is less than half nominal value, 
as during cold starting. Article describes oper- 
ation of circuit in detail. Tr, may require series 
RC protection between collector and emitter. — 
R. M. Carter, Variable Voltage-Ratio Transistor 
Converter, Wireless World, Nov. 1975, p 519. 



2 16 
low leakage indu 

T, 



'1 



1 12V 



Dii 
IN4002 



8-2H 
3W 




IN4002 



-w- 



Tr, 




iov 

400mV 
("22k 



R 4 
22 k 



:ci 

500V 



D 



H 



21 DIOI 

IN4002 



CJ 



CJ07 
22/.F 



-^ 



4002 O 



J 



RI02 

I2A 



QIOI.QI02-D40C6 




9 BRI03 MDA920-3 




CI05 
150/iF 



. RI08 
FR-IO 



■5 



CI06 
lO^F 



-E- 



-H] 



ALL WIRE NYCLAD OR 
FORMVAR INSULATED 



CRO LOW-VOLTAGE SUPPLY— Developed for 
use as one of supplies for portable CRO, oper- 
ating from battery using sealed rechargeable 
cells supplying 12 V at 2-5 Ah. High-efficiency 
inverter uses two GE D40C6 or RCA 2N5294 



transistors (D101 and D102) as commutating 
switches for untapped feedback winding of 
power transformer. R102 then determines 
drive, while R101 produces required unbal- 
anced starting bias. Thermistor R108 in series 
with CRT filament has cold resistance of 10 
ohms to counteract very low cold resistance of 



-E 



CRT filament at start-up and prevent inverter 
malfunction. Article gives instructions for wind- 
ing T101, along with high-voltage supply circuit 
and all other circuits of CRO covering DC to 10 
MHz. — G. E. Friton, Eyes for Your Shack, 73 
Magazine, Nov./Dec. 1975, p 74-76, 78-88, and 
90-94. 



CONVERTER CIRCUITS — DC TO DC 



191 



C2 _L R2 
0.001)1 F -p 6.2K 

\01 





28-V HIGH-EFFICIENCY— Uses driven-type con- 
verter in which signal source is simple two-tran- 
sistor oscillator Q1-Q2. Tum-on delay technique 
eliminates overlap current otherwise flowing in 
2N1016 push-pull power transistors Q5 and Q6 
when one is still on in storage state while other 
is driven on. Efficiency can approach 90%. Q3 
and Q4 prevent off transistor from conducting 
until opposite device has turned off. Values for 
T2, CR3, and CR4 in output circuit are chosen to 
give desired DC output voltage.— R. F. Downs, 
Minimize Overlap to Maximize Efficiency in Sat- 
urated Push-Pull Circuits. EDNIEEE Magazine, 
Feb. 1,1972, p 48-50. 



12 V TO -11 V WITH TRANSISTORS— Bipolar 
inverter and rectifier together provide -11 V 
from 12-V auto battery for operating high- 
threshold MOS logic of portable or automotive 
equipment. Transistor and diode types are not 
critical. Multivibrator draws only 1.2 mA from 
battery on standby and supplies 12 mA from 
negative output terminal.— B. Fette, Inexpen- 
sive Inverters Generate V^ for Portable MOS 
Applications, EDNIEEE Magazine, Dec. 15, 1971, 
p51. 




T60I SEC 
GND 6 



I 



T60I PRIMARY 



n m m 



€) 



"O 



_rC202 



CRO HIGH-VOLTAGE SUPPLY— Controlled in- 
verter operates from 12-V battery and feeds 
positive and negative triplers for producing 
±600 V required for portable CRO. T601 high- 



-600 



t_LC203 

£ 68 



5 



0205 

-w— 



D206 

-w- 



R206 

IO0K 

— VA — 



D203 

IN4762 

eav 



D207 

-X- 



D209 

-w- 



r*' 



&R204 
flMEG 

HV SET 
iR205 
F 270K 



=rC2^ 



D209 

-w- 



600 



D2I0 

-w- 



0204 
IOOV 
IN4764 



voltage transformer has 22K, 5.2K, and 600-ohm 
windings, all center-tapped, often marked "Lio- 
nel" when available in surplus shops. Q201, 
Q202, and Q204 are 2N697 or 2N2219. Q203 is 



NOTE-T60I PINS 3 84 STRAPPED 

D20I, D202-IN4002 
0205 THRU 0210- IN506I 

2N4302 or 2N5457— G. E. Friton, Eyes for Your 
Shack, 73 Magazine. Nov./Dec. 1975, p 74-76, 
78-88, and 90-94. 



192 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+6VDC 

o- 



R EMOTE SHUTDOWN < 



PEAKINVERSE *110V>. 1N2071 



o- 

GND. 



BACK EMF 
; + 30V^ 

2 N 3054 




ru 

r*-*J3(VSEC 



Ic, 



> 



: 22^ F 
1 35V 



^ 



NE550A 3 



J"* 100pF R 6 S2.2k 



'" °^ 



I " 



6 V TO ±15 V — Combination of 555 timer and 
two NE550 voltage regulators provides voltage 
multiplication along with regulation of indepen- 
dent DC outputs. Selected oscillator frequency 
of 17 kHz optimizes performance of trans- 
former. Can be used to power opamps from 
either TTL supplies or 6-V batteries. Line and 
load regulation are 0.1%, while power efficiency 
at full load of 100 mA is better than 75%.— R. 
Solomon and R. Broadway, DC-to-DC Converter 
Uses IC Timer, EDN Magazine, Sept. 5, 1973, p 
87, 89, and 91. 




+12 VTO -8 V — Developed for use with mobile 
equipment when DC voltage is required with 
opposite polarity to that of auto battery. U1 is 
555 timer operated as free-running square- 
wave oscillator. Frequency is determined by R1, 
R2, and C2; with values shown, it is about 6 kHz. 
CI reduces 6-kHz signal radiated back through 
input lines. For 12-V input, typical outputs are 
-8.4 V at 10 mA, -7.9 V at 20 mA, and -5.7 V 
at 50 mA. All diodes are 1N914, 1N4148, or 
equivalent. — G. A. Graham, Low-Power DC-DC 
Converter, Ham Radio, March 1975, p 54-56. 




-*o 



IN207I (4) 

OR EQUIVALENT -^ 




to-o^ 



CT» CENTER TAP 



LM340T- 

12 



100/iF 
35V 



lOO^F 
35V 



LM320T- 
12 



4.7^F 
25 



4.7,»F 
25V 



+ I2V 
AT .2 A 



-I2V 
AT.2A 
O 



± 12 V FROM +5V — NE555 timer connected as each polarity. Circuit uses push-pull inverter mary and 350 turns No. 26 center-tapped for 

20-kHz oscillator drives pair of D44H4 transis- technique to generate AC for driving trans- secondary. — S. Ciarcia, Build a 5 W DC to DC 

tors through 7437 quad two-input NAND buffer former constructed by rewinding 88-mH toroid Converter, BYTE, Oct. 1 978, p 22, 24, 26, 28, and 

to produce full 200 mA of regulated output for to have 40 turns No. 20 center-tapped for pri- 30-31. 



CONVERTER CIRCUITS — DC TO DC 



193 




-Q 4 =2N3643 
1k C.T. : 200k INPUT TRANSFORMER 



0.01 (iF 




5 V TO 400 V— Astable MVBR operating at 2.174 
kHz for values shown drives push-pull transis- 
tor pair feeding primary of audio input trans- 
former T,. Secondary voltage is rectified by 
diode bridge to provide DC output voltage rang- 
ing from 100 to 400 V depending on load resis- 
tance and exact value of supply voltage V cc . 
Bridge rectifier can be replaced by 40-stage mul- 
tiplier as shown in lower diagram, to give 10- 
kVDC output.— A. M. Hudor, Jr., Power Con- 
verter Uses Low-Cost Audio Transformer, EDN 
Magazine, April 20, 1977, p 139. 



• ADD ADDITIONAL STAGES AS REQUIRED 

• DIODES ARE 1N649 0R EQUIVALENT 

• CAPACITORS ARE CERAMIC DISC 1 kV 



280 V TO 600 V— Cascode push-pull transistor 
switch conversion circuit uses low-voltage tran- 
sistors and provides automatic equalization of 
transistor storage time. Drive-signal input to 
cascode push-pull switch is symmetrical 50-kHz 
15 V P-P square wave from 50-ohm source. Q1 
and Q2 each see only half of DC source voltage 
because CI and C2, in series across 280-V input, 
charge to 140 V each. Circuit is adaptable to 
wide range of output voltages and currents be- 
cause identical units can be connected in series 
or parallel to obtain desired rating. — L. G. 
Wright and W. E. Milberger, HV Building Block 
Uses Series Transistor Switches, EDN Maga- 
zine, Feb. 15, 1971, p 39-40. 



280V DC 



50 kHz SQUARE WAVE DRIVE 
15V PK-PK FROM 50t! SOURCE 

o 




I 1 

| 22K ?k270pF 



IC2 
74C04 



T 
I 



15V 



ALL CAPACITORS- 50V DISC CERAMIC 
ALL RESISTORS- I/4W 5% 




IN9I4 

-*- 



Dl 

IN4745 
16V 






-o 



-I5V 
AT 10mA 



-15 V FROM +15 V— First two sections, of 
74C04 hex inverter form 100-kHz oscillator, with 
other sections connected to provide inversion 
of standard microprocessor source voltage as 
required for some interfaces and some D/A con- 
verters. Shunt regulator formed by D1 and Q1 
maintains output voltage relatively constant. 
Changing zener Dl to 13 V makes output -12 
V. — S. Ciarcia, Build a 5 W DC to DC Converter, 
BYTE, Oct. 1978, p 22, 24, 26, 28, and 30-31. 



194 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




V OUT=- 7V 6 



+5 V TO -7 V— Uses LM555 timer as variable- 
duty-cycle pulse generator controlling transis- 
tor switch Q, which in turn drives flyback circuit. 
Regulator 0. 2 -D 3 -Ri-R 5 varies duty cycle accord- 
ing to load, and flyback circuit L-D.-C, develops 
negative output voltage. When Q, is on, current 
flows through L to ground. When Q, turns off, 
polarity across L reverses, diode becomes for- 
ward-biased, and negative voltage appears 
across C, and load. When Q, turns on again, 
voltage across L reverses for start of new cycle. 
Circuit eliminates separate transformer supply 
for negative supply of microprocessor. Effi- 
ciency is about 60%, load regulation 1.3%, and 
supply rejection 30 dB. Article gives design 
equations. — P. Brown, Jr., Converter Generates 
Negative jtP Bias Voltage from +5V, EDN Mag- 
azine, Aug. 5, 1977, p 42, 44, and 46. 



DC MULTIPLIERS— Voltage output from posi- 
tive voltage booster (+12 VDC to +20 VDC) is 
increased by using diode-capacitor voltag'e- 
doubler sections as shown. Diodes are 1N914, 
1N4148, or equivalent. Doubling is achieved at 
expense of available current. Same technique 
may be used to increase output of DC/DC con- 
verter having negative output voltage. — G. A. 
Graham, Low-Power DC-DC Converter, Ham 
Radio, March 1975, p 54-56. 




BUFFER DRIVER- 



DIODE /CAPACITOR, 
MULTIPLIER 



K> 



t>^>^: 




APPROX 6V 
AT 3mA 



o- 



+8 V FROM +5 V— Oscillator operating at 
about 16 kHz steps up 5-V supply voltage of 
microprocessor to 8 V for driving special inter- 
face circuits. Sections c, d, and e of 7404 hex in- 
verter form buffer and driver for voltage-dou- 
bling rectifier. — S. Ciarcia, Build a 5 W DC to DC 
Converter, BYTE, Oct. 1978, p 22, 24, 26, 28, and 
30-31. 




POLARITY REVERSER— Simple RC oscillator 
operating at about 1200 Hz can be used with 
choice of rectifier circuits to provide negative or 
positive voltages equal to or higher than DC 
supply, without use of transformer. Output 
transistors connect load alternately to positive 



supply and to ground for high operating effi- 
ciency. Two-diode voltage doubler with con- 
nection to 12-V supply gives positive output. 
Other diode rectifier circuit doubles oscillator 
output and gives negative supply. Negative 



doubler uses switching transistors. All three 
rectifier circuits provide common ground from 
supply to output. — J. M. Pike, Negative and 
High Voltagesfrom a Positive Supply, QST, Jan. 
1974, p 23-25. 



CONVERTER CIRCUITS — DC TO DC 



195 



± 15 V FROM +5 V— Provides positive and neg- 
ative higher voltages required by some inter- 
face devices used with microprocessors. NE555 
timer is connected as 100-kHz oscillator that 
switches transistor on and off, inducing current 
in primary of T1. High-voltage spike reflected 
back to collector of transistor by pulse trans- 
former is routed through D1 to filter-regulator 
for providing positive output— S. Clarcia, Build 
a 5 W DC to DC Converter, BYTE, Oct. 1978, p 
22, 24, 26, 28, and 30-31. 



I 3.3K 



T 



.001 



IC4 
NE555 

V OUT 




J "> -I5V AT 
t m n a 



_| V+I5V AT 



ALL RESISTORS - l/«*,S% EXCEPT WHERE NOTED 

T, IS A PULSE ENGINEERING TRANSFORMER PE-3643 



vcc 
O 



2 kH* CLOCK 

o 



R A = 1K 
-^vW- 



SIGNETICS 
555 



100 £F 

-If- 



-pO.OI^F -T^0.01/|F 



F>B " 33K 



1N916 

-w- 



10K 



VlN9 



16 



-O-v 



OUT 



ifc100/«F 

-O 



TRANSFORMERLESS POSITIVE TO NEGA- 
TIVE — Used to derive negative supply voltage 
from positive supply voltage, while at same 
time generating 2-kHz clock signal. Negative 
output voltage tracks DC input voltage linearly, 
but magnitude is about 3 V lower. Circuit does 
not provide regulation. — "Signetics Analog 
Data Manual," Signetics, Sunnyvale, CA, 1977, 
p729. 



198 ma 



rAAA— , 
■i- l 




/ wv — wv wv — vw- 

(NINE 2i Mfl RESISTORS IN. SERIESI 



IN9I4 

YELLOWl [RED 



J. I * j 

-i-0.01 -±- RCA 
%F ADI20IP ' 
AT I KV \ 

1 ►! 1 r ' 

Jblue rca 

: DI20IP loo, 
-t m f 

pen ATIKV 



RCA iO.OI 

F 
AT IKV 



ARG0NNE 
TYPE ARI42 



T 



REGULATED +900 V FROM +6 V— CA3094 pro- 
grammable opamp is connected as oscillator for 
driving step-up transformer that develops suit- 
able high voltage for rectification in diode net- 
work. Sample of +900 V regulated output is fed 



REGULATED HI6H-V0LTAGE SUPPLY 
to CA3080A variable opamp through 198-meg- is within 1% for loads of 5 to 26 iiA. DC-to-DC 
ohm resistor of voltage divider to control pulse conversion efficiency is about 50%.— "Circuit 
repetition rate of oscillator. Magnitude of reg- Ideas for RCA Linear ICs," RCA Solid State Di- 
ulated output is controlled by pot R. Regulation vision, Somerville, NJ, 1977, p 19. 



196 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



OTO -10V FROM +12 V— Variable-output con- 
verter using NE555 timer delivers negative out- 
put voltage required by some interface devices 
and D/A converters used with microproces- 
sors. — S. Ciarcia, Build a 5 W DC to DC Con- 
verter, BYTE, Oct. 1978, p 22, 24, 26, 28, and 30- 
31. 



IC3 
NE 555 




.' V ADJI 
> 250K 



IN9I4 

H« f 



\f IN9I4 

/77 rh 



25V 



~ AT lOir 



( + 10Vto + 15V) 




15VTO -24 V — Voltage doubter is used in com- 
bination with 555 astable MVBR and two peak- 
to-peak detectors to give high negative volt- 
ages from positive voltage source. Load current 



capability is about 10 mA. Output drops to 
about -14.5 V when using supply of +10 V. — 
W. G. Jung, "IC Timer Cookbook," Howard W. 
Sams, Indianapolis, IN, 1977, p 197-201. 




+12 V TO +20 V — Developed for use with mo- 
bile equipment when DC voltage higher than 
that of auto battery is needed. One application 
is trickle-charging 12-V nickel-cadmium batter- 
ies. U1 is 555 timer operated as free-running 
square-wave oscillator. Frequency is deter- 
mined by R1, R2, and C2; with values shown, it 
is about 6 kHz. C1 reduces 6-kHz signal radiated 
back through input lines. If converter is used 
with high-frequency receiver, insert 100-pH RF 
chokes in power leads to suppress harmonics 
of 6 kHz. For 12-V input, typical outputs are 20.4 
V at 10 mA, 19.9 V at 20 mA, and 17.7 V at 50 
mA. All diodes are 1N914, 1N4148, or equiva- 
lent. — G. A. Graham, Low-Power DC-DC Con- 
verter, Ham Radio, March 1975, p 54-56. 




+12 V TO -12 V — High-efficiency polarity in- 
verter for mobile applications provides well- 
regulated adjustable negative output voltage at 
2 A from positive auto battery source. Stable 
UJT oscillator Q1 drives transistor 02 to pro- 
duce symmetrical square wave. Q3 buffers out- 
put and furnishes driving power for inverter Q4 
and output stage Q7. Q4 and Q5 together drive 
Q6 into complete saturation. Q6 and Q7 form 
complementary-symmetry output operating in 
saturation mode, with only one transistor 
turned on at a time. As they are alternately 
switched on and off, square wave alternating 



between ground and nearly battery potential is 
applied to C3. Q10 and Q11 are connected as 
diodes for clamping square wave negatively. 
Output voltage is regulated by transistor feed- 
back loop Q8 and Q9, with zener CR2 providing 



stable reference. R10 is 100 ohms for 2 A maxi- 
mum; increasing its value improves efficiency 
but reduces maximum current. — J. R. Laughlin, 
Medium Current Polarity Inverter, Ham Radio, 
Nov. 1973, p 26-30. 



CONVERTER CIRCUITS — DC TO DC 



197 



OUTPUT 
(APPR0X-12V) 




+15 V TO -12 V— Simple transformerless 
power converter uses 555 timer in self-triggered 
mode as square-wave generator, followed by 
voltage-doubling rectifier. Values shown for R 
and C give frequency of about 20 kHz, which 
permits good filtering with relatively small ca- 
pacitors. Maximum load current is about 80 
mA. — M. Strange, IC Timer Makes Transformer- 
less Power Converter, EDN Magazine, Dec. 20, 
1973, p 81. 



± 1 5 V FROM 12 V— Steps up output of 12-V bat- 
tery to voltages required by PLL such as NE561. 
Uses 900-Hz sine-wave oscillator and LM380N 
AF amplifier to drive voice-coil side of standard 
500-ohm to 3.2-ohm output transformer having 
bridge rectifier across center-tapped primary. 
With 10-mA loads, maximum ripple is 15 mV P- 
P. With receiver quiet, 900-Hz hum is audible, 
but is normally lost under background noise. 
Oscillator choke (about 700 mH) is 800 turns of 
No. 44 magnet wire in Ferroxcube 3C pot 
core. — R. Megirian, Build a Noise-Free Power 
Supply, 73 Magazine, Dec. 1977, p 208-209. 





ilN4153 OUTPUT 
IAPPROX *27V> 
W T ° 

IN4153 



lOOOpF 



, 22/jF 
' 35V 



+15 V TO +27 V— Uses 555 timer in self-trig- 
gered mode as square-wave generator operat- 
ing at about 20 kHz, followed by voltage-dou- 
bling rectifier. Provides approximate doubling 
of voltage without use of transformer. Maxi- 
mum load current is about 80 mA. — M. Strange, 
IC Timer Makes Transformerless Power Con- 
verter, EDN Magazine, Dec. 20, 1973, p 81. 



CHAPTER 18 

Converter Circuits — Digital-to-Analog 



Includes circuits for converting variety of digital inputs to linearly related 
analog output voltage or current, providing analog sum of two digital inputs, 
or converting stored digital speech back to analog form. 



> V CC +16V TO +30V 




8-BIT BINARY TO PROCESS CURRENT— Uses of 4-20 mA. Fixed current of 0.5 mA is added to 

only three Precision Monolithics ICs operating DAC output current varying between and 2 

from -5 V and +23 V supplies to convert 8-bit mA, with resulting total current multiplied by 

binary digital input to process current in range factor of 8 to give up to 20 mA through 500-ohm 

198 



load.— D. Soderquist, "3 IC 8 Bit Binary Digital 
to Process Current Converter with 4-20 mA Out- 
put," Precision Monolithics, Santa Clara, CA, 
1977,AN-21. 



CONVERTER CIRCUITS — DIGITAL-TO-ANALOG 



199 



HIGH-SPEED OUTPUT OPAMP— Precision 
Monolithics OP-17F opamp optimizes DAC-08E 
D/A converter for highest speed in converting 
DAC output current to output voltage up to 10 
V under control of digital input. Settling time is 
380 ns— G. Erdi, "The OP-17, OP-16, OP-15 as 
Output Amplifiers for High Speed D/A Convert- 
ers," Precision Monolithics, Santa Clara, CA, 
1977, AN-24, p 2. 



DIGITAL 
INPUTS 




5l 6| 7I 8| 9| 10I 111 12l 



1.25KS2 
3_1_„ 



B1 B2 B3 B4 B5 B6 B7 B8 




V n .Oto+lOV 




FOUR-CHANNEL BCD— Uses four Precision 
Monolithics DAC-20CQ 2-digit BCD D/A con- 
verter, OP-11FY precision quad opamp, and 
REF-01H J + 1 V voltage reference to convert 2- 
dight BCD input coding to proportional analog 
to +10 V output for each of four channels. 
Same configuration will handle binary inputs, 
as covered in application note. For output range 
of to +5 V, change voltage reference to REF- 
02.— D. Soderquist, "Low Cost Four Channel 
DAC Gives BCD or Binary Coding," Precision 
Monolithics, Santa Clara, CA, 1977, AN-26, p 3. 



200 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



10 V LOGIC INPUTS 



® © © Y © © © 



® © © 





r©- 


V( 








CA3085 "*S— (e 




K^ 


Sx. ® > 


1 (V) 




C*) I 




25 V 


001 /i 


f * 












9-BIT USING DIGITAL SWITCHES— Combina- 
tion of CD4007A multiple-switch CMOS ICs, lad- 
der network of discrete metal-oxide film resis- 
tors, CA3160 voltage-follower opamp, and 
CA3085 voltage regulator gives digital-to-ana- 
log converter that is readily interfaced with 10- 
V logic levels of CMOS input. Required resistor 
accuracy, ranging from ±0.1% for bit 2 to ±1% 
for bits 6-9, is achieved by using series and par- 
allel combinations of 806K resistors. — "Linear 
Integrated Circuits and MOS/FET's," RCA Solid 
State Division, Somerville, NJ, 1977, p 267-268. 



6 BITS TO ANALOG— Uses Motorola MC1723G 
voltage regulator to provide reference voltage 
and opamp for MC1406L 6-bit D/A converter. 
Output current can be up to 150 mA. Full-scale 
output is about 10 V, but can be boosted as high 
as 32 V by increasing value of R 2 and increasing 
+15 V supply proportionately to maximum of 
35 V.— D. Aldridge and K. Huehne, 6-Bit DIA 
Converter Uses Inexpensive Components, EDN 
Magazine, Dec. 15, 1972, p 40-41. 



DIGITAL 
INPUTS I 

(MSB) AlO-S{ 




A20-^ 
A30-2JLAD 

RjCURRENT 
A4O ~~lC0NVERTER 
A50^ 

A6012! 




LOW PASS FILTER 



I0 M F lO^F 

«6 




DAC FOR SPEECH— Audio signals stored in 8- 
channel digital form in computer are converted 
back into analog form for feed through low-pass 
filter to input of audio amplifier. Can be used for 
computer-controlled synthesis of speech from 



phonemes in any language or for providing 
voice replies to queries. Pin 7 of IC9 is +12 V, 
and pin 4 is - 12 V. — S. Ciarcia, Talk to Mel Add 
a Voice to Your Computer for $35, BYTE, June 
1978, p 142-151. 



CONVERTER CIRCUITS — DIGITAL-TO-ANALOG 



201 



MSD 




-15V 



LSD 



laJPH 



20- 

1 1 o- 



OTO 9 9V 

IN IV STEPS 



Vfs *9 9V FOR 

(1001 1001) CODE 



2-DIGIT BCD INPUT— Each Signetics 5007/5008 
multiplying D/A converter serves one digit of 
input voltage to give output current that is 
product of digital input number and input ref- 
erence current. Opamp combines currents and 
converts them to analog output voltage pro- 
portional to digital input value. — "Signetics An- 
alog Data Manual," Signetics, Sunnyvale, CA, 
1977, p 677-685. 



ANALOG SUM OF DIGITAL NUMBERS— Two 
Precision Monolithics DAC-100 D/A converters 
and OP-01 opamp combine conversion with 
adding to give high-precision DC output volt- 
age. 200-ohm pots are adjusted initially to give 
exactly desired output for input of all 0s.— "8 
& 10 Bit Digital-to-Analog Converter," Precision 
Monolithics, Santa Clara, CA 1977, DAC-100 
P5. 




Nz mmmi 



V 0UT = N,+N 2 




Clock input 



SIMPLE DAC— Transistors are either saturated 
or cut off by outputs of clock-controlled SN7490 
BCD counter. Portions of emitter voltages of the 
four transistors are added in ratios 1:2:4:8 by 
741 summing opamp to obtain analog output. 
Article tells how two such circuits can be com- 
bined for use in two-digit DVM. — D. James, 
Simple Digital to Analogue Converter, Wireless 
World, June 1974, p 197. 



202 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 5V 




TEMPERATURE COMPENSATION —Use of 7407 
hex buffer following SN7490 of D/A converter 
permits satisfactory performance over reason- 
ably wide temperature range even when driving 
several TTL stages. Noninverting input of 741 
opamp is connected to output of unused buffer 
at logic 0. Circuit is modification of D/A con- 
verter developed by D. James for use in simple 
two-digit DVM. — R. J. Chance, Improved Sim- 
ple D. to A. Converter, Wireless World, Dec. 
1974, p 503. 



N|o miiffii 



2-DIGIT BCD — Output current of Precision Mon- 
olithics DAC-100 D/A converter can be adjusted 
to exactly desired value with 200-ohm pot for 
each DAC; adjustment is made with input of all 
Os. Circuit can be expanded to 3 digits by adding 
third DAC and adding 99 to current divider. — 
"8 & 10 Bit Digftal-to-Analog Converter," Pre- 
cision Monolithics, Santa Clara, CA, 1977, DAC- 
100, p 5. 




N mi 



}9 TO I CURRENT* 
DIVIDER 




ZVDIGIT INPUT FOR 199 COUNT— Addition of 
Vdigit circuit to basic 2-digit BCD DAC in- 
creases count from 99 to 199. Circuit sequences 
to 99 while 1 ^-digit section of MC14009 hex two- 
input NOR gate has low output, and goes 
through steps 100 to 199 while 'A-digit output 
is high. Reference voltage is 5.0 V. Calibration 
procedure is given. — T. Henry, Binary D/A Con- 
verters Can Provide BCD-Coded Conversion, 
EDN Magazine, Aug. 5, 1973, p 70-73. 



DIGIT 



1/2 SCALE CAL 



CONVERTER CIRCUITS — DIGITAL-TO-ANALOG 



203 



i 



Vcc + 16V to +30V 

D1 D2 D3 D4 
1N4001'S 



R5 
80012 

0.5 to ^>±0.1% 

2.5 mA 




CURRENT CONVERTER— Converts 8-bit TTL 
digital inputs to process current in range of 4 to 
20 mA, for microprocessor control of industrial 
operations. Fixed 0.5-mA current is added to 
DAC output current varying between and 2.0 
mA and multiplied by factor of 8 to produce final 




Output voltage 
compliance (Voc) 



Vcc 


Voc 


16V 


10V 


23V 


17V 


30V 


24V 



-20KS! « Settling time a 5 /jsbc 
"4% ±1% tt with R L = 500 a 



output current of 4-20 mA. To calibrate, con- 
nect ammeter between output and ground, 
then apply +23 V+7V and -5 V ± 1 V to con- 
verter. Make digital inputs all 0s (less than +0.8 
V). Adjust R1 until output current is 4.0 mA. 



Change digital inputs to all 1 s (greater than +2.0 
V), and adjust R2 until output current is 20 
mA. — D. Soderquist, Build Your Own 4-20 mA 
Digital to Analog Converter, Instruments & 
Control Systems, March 1977, p 57-58. 



R = 40 kn ± 1 % 




CLOCK OPTION 



fOrO 

> 200k > 100k 



AUTOREFERENCE— National CD4024C con- 
verter is used with logic and summer elements applications having short repeated duty cycles, sphygmomanometers. Circuit eliminates 
toeliminatevirtualfyalloffseterrorsinducedby each containing reference point. Examples in- warm-up errors.— "Pressure Transducer Hand- 
time and temperature changes in process con- dude weighing scale in which transducer is load book," National Semiconductor, Santa Clara, 
trol system fed by transducer. Best suited for cell, pressure control systems, fuel pumps, and CA, 1977, p 7-4-7-8. 



204 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



V REF 
O*10V 



5K<; 

! REF 



DIGITAL 

lA'i INPUT 

WORD 



DAC-08 

»2 



DIFFERENTIAL CURRENT 



UHiiii 



iiiiilii 



DIGITAL 
(B\ INPUT 
WORD 



--o — 




l 0UT TO BALANCED LOAD 





'OUT" '01- l 2 sK li A! * r Bi! 

V REF 
K - s AND "A" AND "B" 

H REF 
ARE POSITIVE OR NEGATIVE 
OFFSET BINARY DIGITAL WORDS 



WORD "A" 


WORD "B" 


'01 


'02 


E OUT 


1111 1111 


1111 1111 


3.984mA 





+9.96V 


1100 0000 


1100 0000 


3.000mA 


0.984mA 


+5 .04V 


1000 0001 


0111 1111 


2.000mA 


1 984mA 


+0.04V 


1000 0000 


0111 1111 


1.992mA 


1 992mA 





0111 1111 


1000 0000 


1.992mA 


1.992mA 





0111 1110 


1000 0000 


1.984mA 


2.000mA 


-0.04V 


0011 1111 


0011 1111 


0.984mA 


3.000mA 


-5.04V 


0000 0000 


0000 0000 





3.984mA 


-9.96V 



FOUR-QUADRANT ALGEBRAIC— Two Preci- 
sion Monoiithics DAC-08 D/A converters per- 
form fast algebraic summation of two digital 
input words and feed OP-02 opamp that pro- 
vides direct analog output which is algebraic 
sum of words A and B in all four quadrants. — J. 
Schoeff and D. Soderquist, "Differential and 
Multiplying Digital to Analog Converter Appli- 
cations," Precision Monoiithics, Santa Clara, 
CA, 1976, AN-19, p 7. 



5V ANALOG INPUT 
° ° 



SERIAL 
OUTPUT 



CHORD BITS 




BELL-SYSTEM fi-255 COMPANDING LAW— 
Precision Monoiithics DAC-86 is used in circuit 
that provides 15-segment linear approximation 
by using 3 bits to select one of eight binarily re- 



lated chords, then using 4 bits to select one of 
sixteen linearly related steps within each chord. 
Sign bit determines signal polarity, and encode) 
decode select bit determines operation. Circuit 



shown is for parallel data applications. Forserial 
data, omit inverter, two 74175 chips, and half of 
7474. Power supplies should be well by- 
passed. — "COMDAC Companding D/A Con- 
verter," Precision Monoiithics, Santa Clara, CA, 
1977, DAC-86. p 6. 



CHAPTER 19 

Converter Circuits — General 



Includes V/F, V/l, V/pulse width, V/time, F/V, 7-segment/BCD, BCD/7-segment, 
Gray/BCD, Gray/binary, binary/BCD, time/V, pulse height/time, l/V, and other 
converter circuits for changing one parameter linearly to another. See also 
other Converter chapters. 




10 Hz T0 10 kHz V/F— External circuit shown for 
Teledyne 9400 voltage-to-frequency converter 
provides means for trimming zero location and 
full-scale frequency value of output. For 10-kHz 



full-scale value, set V, N to 10 mV and trim with 
50K offset adjust pot to get 10-Hz output, then 
set V lN to 10.000 V and trim either R IN , V„ EF , or 
C„ EF to obtain 10-kHz output.— M. O. Paiva, 



"Applications of the 9400 Voltage to Frequency 
Frequency to Voltage Converter." Teledyne 
Semiconductor, Mountain View, CA, 1978, AN- 
10, p 3-5. 



205 



206 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



C, .005 u\ 



v tt> 



R B 100ki; 



-wv- <► 



+v 



FULL SCALE TRIM 
5ki! 12 ki! 



HH 




TO-V r 




OUTPUT 
FREQUENCY 

0^f o ^ 10 kHz 



(l |f-*-VW 



o VW 1 




■=■ c o 



V/F CONVERTER WITH 0.05% LINEARITY— Ray- 
theon RM4151 converter is used with integrator 
opamp to give highly linear conversion of inputs 
up to -10 VDC to proportional frequency of 
square-wave output. With maximum input of 
- 1 V, adjust 5K full-scale trimpot for maximum 
output frequency of 10 kHz. Set offset adjust pot 
to give 10-Hz output for input of -10 mV. To 
operate from single positive supply, change 
opamp to RC3403A. — "Linear Integrated Circuit 
Data Book," Raytheon Semiconductor Division, 
Mountain View, CA, 1978, p 7-38. 



.01 of 6.8 k<> 



0.1 Hz-100 kHz VfF— Uses NE556 timer in dual 
mode in combination with opamp and FET for 
linear voltage-to-frequency conversion with 
output range from 0.1 Hz to 100 kHz. Operating 
frequency is 0.91/2RC where R is resistance of 
FET.— K. Kraus, Linear V-F Converter, Wireless 
World, May 1977, p 80. 




BCD 


GRAY 


X-3 GRAY 


0000 


0000 


0010 


0001 


0001 


0110 


0010 


0011 


0111 


0011 


0010 


0101 


0100 


0110 


0100 


0101 


0111 


1100 


0110 


0101 


1101 


0111 


0100 


1111 


1000 


1100 


1110 


1001 


1101 


1010 



LSB 



SN7476 



1 31 3?lT + 



EXCESS-THREE GRAY CODE TO BCD— Devel- 
oped for use with shaft encoder providing ex- 
cess-three Gray-code output. Requires only two 




BCD 



TTL ICs, connected as shown. To convert regu- 
lar Gray code to BCD, omit SN7483 4-bit adder. 
Tabulation shows how circuit accomplishes 



conversion for both types of Gray codes. — D. M. 
Risen, Two ICs Convert Excess-Three Gray Code 
to BCD. EDN Magazine, Nov. 1, 1972, p 44. 



CONVERTER CIRCUITS-GENERAL 



207 



C| .002 (if 



o < v. < +iov o WV 



r 

_L 5Kn 



'o o 



OUTPUT FREQUENCY 
0< f <10k Hz 




HIGH-PRECISION V/F CONVERTER— Active in- 
tegrator using one section of RC3403A quad 
opamp improves linearity, frequency offset, and 
response time of Raytheon RM4151 converter 
operating from single supply. Opamp develops 
null voltage. — "Linear Integrated Circuit Data 
Book," Raytheon Semiconductor Division, 
Mountain View, CA. 1978, p 7-38. 



+ V CC 



DC VOLTAGE TO TIME— Opamp connected as 
integrator feeds opamp comparator to produce 
output pulse whose width is proportional to 
magnitude of DC input voltage. Circuit shown 
is for positive inputs only; for both positive and 
negative inputs, article tells how to add another 
comparator. Circuit can then be used to gener- 
ate start and stop pulses applied to digital timer 
of digital voltmeter. — G. 6. Clayton, Experi- 
ments with Operational Amplifiers, Wireless 
World, Sept. 1973, p 447-448. 




_t~l 



+ 15VQ 



r 



+ o- 

INPUT 
200 VDC 



-VW- 

100k 



HP 5082-4360 



-VVSA- 

10k 



X 0.001 ■] 

T°° I 



r 



Q+5V 



OUTPUT 

— — o 



TO DIGI.TAL 
FREQUENCY COUNTER 
WITH GO/NO GO 
LIMIT COMPARITOR 



innr 



VOLTAGE-TO-FREQUENCY GO/NO-GO— Sin- 
gle UJT is used as V/F converter to provide com- 
pletely isolated inputs and outputs for high- 
voltage go/no-go test monitor. When voltage 



exceeds predetermined limit, output to digital 
frequency counter exceeds corresponding fre- 
quency limit. Output can be fed directly into dig- 
ital frequency-limit detector that provides go/ 



no-go indication . — T. H. Li, VFC Used in Isolated 
GO/NO GO Voltage Monitor, EDN Magazine, 
July 5, 1974, p 75. 



208 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



INPUT 
0TO 10 V 



100K 



i C 2 
rr ^ 1b0pF 



| ^ 



«6 
10K 

■Wv- 



• — *■ RAMP OUTPUT 



1000 pF 




•«2 
• 100K 



"5 
■ 15K 



R 4 
5 1M 



15 V 

o 



^ 30 pF 



-O OUTPUT 



-O OUTPUT 



VOLTAGE TO FREQUENCY— Input voltage 
range of to -10 VDC is converted by opamp 
and timer to proportional frequency with good 



linearity. Circuit is TTL-compatible. Accuracy is 
0.2%. — "Signetics Analog Data Manual," Sig- 
netics, Sunnyvale, CA 1977, p 727-729. 




CURRENT TO VOLTAGE— Developed for use 
with current-output transducers such as silicon 
photocells. For widest frequency response, cir- 
cuit values may need some adjusting for source 
current and capacitance. C„ across feedback re- 
sistor of opamp, eliminates ringing around 500 
kHz. If input coupling capacitor is added to re- 
duce DC gain, circuit can be used with inductive 
source such as magnetic tape head. — R. S. Bur- 
wen, Current-to-Voltage Converter for Trans- 
ducer Use, EDN Magazine, Dec. 15, 1972, p 40. 



0.01-10 Vto 1, 10, OR 100 kHz— Simple voltage- 
to-frequency converter uses Raytheon 4152 op- 
erating from single 15-V supply to convert an- 
alog input voltage to proportional frequency of 
square-wave output. Maximum output fre- 
quency depends on values used for resistors 
and capacitors, as given in table. Suitable for 
applications where input dynamic range is lim- 
ited and does not go to zero.— "Linear Inte- 
grated Circuit Data Book," Raytheon Semicon- 
ductor Division, Mountain View, CA, 1978, p 
7-45-7-46. 



_1_ 5 KH 15 K« 




0.01 (if 



REF 



GATED 
CURRENT 
SOURCE 



COMPARATOR 



:=> 



Operating 
Range R 



-K 



♦ v cc 




3 OUTPUT i 



inn 



DC to 1 kHz 
DC to 10 kHz 
DC to 100 kHz 



6.8 KS2 
6.8 K« 
6.8 KH 



0.1 *iF 
0.01 mF 
0.001 (jF 



100 KO 10,uF 
100 KS1 1.0 jjF 

100 kh o.i mf 




20k 
■WNA- 




v 20k 



5pF 



10k 




V../2 



440k 

RMS-TO-DC 

CONVERTER 



T 




20-kHz SQUARE-WAVE TO DC— Provides ac- 
curacy within 0.1% for square-wave inputs of 3 
to 7 VRMS in frequency range of 5 to 20 kHz 
when duty cycle is 50%. Opamps A, and A 2 are 



connected as differential input voltage-follow- 
ers to provide high input impedance. A 3 con- 
verts to single-ended output as required by 
Model 440 converter IC. A, provides adjustable 



gain than roughly offsets attenuation of A3, with 
2K pot being adjusted to provide desired ratio 
of DC output voltage to RMS value of input. — 
J. Renken, Differential High-Z RMS-DC Con- 
verter Has 0.1% Accuracy, EDN Magazine, May 
5, 1977, pi 14 and 116. 



CONVERTER CIRCUITS-GENERAL 



209 




SINGLE-SLOPE V/F CONVERSION— UJT forms 
reference that determines reset point of 
LM301A integrator for converting analog input 
voltage to proportional frequency. Output of in- 
tegrator ramps negative until UJT switches and 
drives output positive at high slew rate. Positive 
edge of integrator output is differentiated by RC 
network and level-shifted by NPN bipolar tran- 
sistor to provide logic-compatible pulse. — J. 
Williams, Low-Cost, Linear A/D Conversion 
Uses Single-Slope Techniques, EDN Magazine, 
Aug. 5, 1978, p 101-104. 



GRAY TO BINARY— Converts first 4 bits of 
Gray-code word to binary output. Uses two 
MC7496 shift registers and logic elements to 
transfer data serially from input register 
through MC1812 EXCLUSIVE-OR IC to output 
register. One requirement is that strobe on pin 
8 of input register must complete its function 
before clock appears on pin 1 of register. When 
this and other timing conditions are satisfied, 
converter will work at speeds up to about 10 
megabits per second. — J. Barnes, "Analog-to- 
Digital Cyclic Converter," Motorola, Phoenix, 
AZ, 1974, AN-557, p 9. 




Binary Output 



V CC *15V O— 



V|N" 



VREF 
2 ' 3 . V CC 



PULSE GENERATOR 
OR SYSTEM 
CLOCK 

Q 




V, N = 



v OUT 
FOR 



VOUT 
FOR 

V|N = V 2 
V 2 V, 



•V, N IS LIMITED TO 2 
DIODE DROPS WITHIN 
GROUND OR BELOW 



VOLTAGE TO 
timer together 



PULSE WIDTH— Opamp and 
convert input voltage level to 



width of output pulse with accuracy better than "Signetics Analog Data Manual,' 
1%. Output is at same frequency as input.— Sunnyvale, CA, 1977, p 726-727. 



Signetics, 



210 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



E, 

o-iov 



90k, 1% 



90k, 1%< 



^2 

0-10V 




NOTE: T : PRIMARY-300 TURNS #36 AWG WIRE 

EACH SECONDARY-75 TURNS #36 AWG WIRE 
CORE MATERIAL-EE24-25 LAMINATIONS OF 



GRAIN-ORIENTED SILECTRON 



DIVIDING ANALOG VOLTAGES— Charge-and- 
dump V/F conversion technique is used to ob- 
tain quotient of two analog voltages digitally. 
Applications include measurement of total 
mass flow of gas under constant pressure. With 
Q, and Q2 normally off, C, charges at rate pro- 



portional to input E„ producing negative ramp 
at output of integrating opamp A,. When R 2 
wiper voltage exceeds E 2 , output of A 2 goes 
high, turning on Q 3 and temporarily driving Q, 
and Q 2 into conduction. This processdischarges 
C,, resetting output of A, to zero. With values 



OUTPUT 
FREQUENCY = f 



shown, E, and E 2 equal, and wiper of R 2 at mid- 
point, circuit output is 10,000 pulses per hour, 
suitable for driving electromechanical counter. 
Output frequency is proportional to average DC 
value of E, even when input changes rapidly. — 
H. L. Trietley, Voltage-to-Frequency Converter 
Performs Division, EDN Magazine, Jan. 5, 1978, 
p 79-80. 



CODED OUTPUT 




BIPOLAR OUTPUT— Low-cost voltage-to-fre- 
quency converter IC is here used in A/D con- 
verter circuit that will accept bipolar inputs and 
generate positive-going pulses to indicate pos- 
itive input voltages and negative-going pulses 
for negative input voltages. Opamps A, and A 2 
form negative-output absolute-value circuit 
that feeds opamp A 3 and RC4151 voltage-to-fre- 
quency converter, for generating 10-jus nega- 
tive-going pulses with repetition-rate scale fac- 
tor of 1 kHz/V. Full-scale input is 20 V P-P. 
Opamp A< is ground-referenced voltage com- 
parator having zener clamp, providing TTL- 
compatible logic output for indicating input 
polarity. Pulse-receiver/decoder section takes 



digitally coded signals arriving from transmit- 
ter, for processing by data line of D flip-flop and 
two trigger inputs of dual-edge retriggerable 
mono MVBR. This generates 25-fts negative- 
going output pulse for each 10-jus input pulse 



from data line. Logic 1 on complementary out- 
put of flip-flop indicates that original input volt- 
age to transmitter was positive. — E. J. DeWath, 
Low-Cost A/D Converter Transmits and Re- 
ceives, EDN Magazine, Jan. 5, 1977, p 35. 



CONVERTER CIRCUITS-GENERAL 



211 




< 3.3 kn L 



2N3906 




D 
1N914 
I, 



-'- l45.3kfi 



2N5089 



+ 1SV o 



Low-Frequency 
Calibrate 



C, 
0.1 ^F 



1N914 
►I 



V+ 



R 
TH 

A 2 OUT 
TR 555 



DIS 



c,*t 

;£ 1000 pF 
1% 



GND 



vr. t, IjAr, + rJ 



V— 

(-10V to 
-15V) 



= 1000 v c 

where, 
R„= 1.818 kn, t, =R, C, = 50 M s, l 2 = 1 mA, 

'R,, C,, R„, and R b are stable, low-TC components 



R, + R, 



1 

77 



JT 

-o Output 

(TTL Compatible) 



POSmVE-INPUT V/F— Input voltages from to timer A 2 provides functions of precision mono voltage output for 555 and 308A.— W. G. Jung, 
10 V are divided by R, and R a for application to MVBR and level sensor. Regulator A 3 acts as "IC Timer Cookbook," Howard W. Sams, Indi- 
noninverting input of current source A,. 555 gated current source and provides stabilized anapolis, IN, 1977, p 184-192. 



+ 15V 




Jl 



Output 2 



Output 1 
( TTL Compatible) 



where, 
t, = R, C, = SO^s, R„ = 20 kn, l 2 = 1 mA. 

+ R,, C,, R a , and R b are stable, low-TC components (see text). 



-15V 



scale value of 10 kHz. Internal regulation of cir- MVBR. Transistor switch Q, connects R„to 3.15- 

-10 V GIVES 10 kHz — Control voltage input in cuit makes operation essentially independent V reference voltage during t, timing period of 

range of to -10 Vis converted linearly to f re- of ±15 V supply level. A, is opamp integrator, A 3 — W.G.Jung, "IC Timer Cookbook," Howard 

quency of digital output pulse train having full- A 2 is comparator, and A 3 is precision mono W. Sams, Indianapolis, IN, 1977, p 184-192. 



212 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




V/F AND F/V— Although based on Raytheon 
4151 IC voltage-to-frequency converter, circuit 
is readily adapted to other modern V/F convert- 
ers now costing under $10 each. With values 
shown, input of to - 10 VDC provides propor- 
tional frequency change from to 10 kHz at out- 



put. Design equations are given. Article also 
covers F/V operation of same IC for demodulat- 
ing FSK data.— T. Cate, IC V/F Converters Read- 
ily Handle Other Functions Such as F/V, AID. 
EDN Magazine, Jan. 5, 1977, p 82-86. 




TIME TO VOLTAGE— Time period of negative 
gating signal determines amplitude of linear 
output ramp generated by integrator opamp. 
Amplitude of ramp, proportional to input time, 
is observed on calibrated screen of oscillo- 
scope. — G. B. Clayton, Experiments with Op- 
erational Amplifiers, Wireless World, Sept. 
1973, p 447-448. 



BLANKO- 




«o- 



lO- 



c O- 



~ V.10 12. ._ 



11 ch 



I 2 



EK-a> 



l^z^o-! 



'^E^ 1 "^^ 



dl^B, 





il^iB)* 11 ^ — ^fe> 



2^ 



-02 1 



-o 2 ° 



DIGIT 


BLNK. 


a 


b 


c 


d 


e 


f 


g 


23 


2 2 


2' 


2° 


























1 














1 





1 








1 


1 


1 


1 











1 


2 











1 








1 











1 





3 

















1 


1 











1 


1 


4 





1 








1 


1 











1 








5 








1 








1 











1 





1 


6 








1 




















1 


1 





7 














1 


1 


1 


1 





1 


1 


1 


8 














Q 











1 











9 

















1 








1 








1 


BLANK 


1 


X 


X 


X 


X 


X 


X 


X 


1 


1 


1 


X 



X = DON'T CARE 

= Ov (SEGMENT ACTIVE) 

1 = + 12V (SEGMENT OFF) 



SEGMENT 
IDENTIFICATION 



7-SEGMENT TO BCD— Uses six CMOS pack- 
ages to convert 7-segment display to corre- 
sponding four-line positive-logic BCD code for 
digits 0-9. Added feature is blank input which. 



when high, forces blank code (1110 or 11 11) into 
readout, for use in suppressing leading zeros 
with some types of data storage. Use 4010 in 
place of 4009 for Z, when negative-logic BCD 



c 2^5 



TYPE 4001 
TYPE 4011 
TYPE 4002 
TYPE 4009 



+ 12V PIN 14 
GND PIN 7 

+ 12V PIN 16 
GND PIN 8 
+5V PIN 1 



output is required. — R. Sturla, Real-Time 7-Seg- 
ment to BCD Converter, EDN Magazine, June 
20, 1973, p 89. 



CONVERTER CIRCUITS-GENERAL 



213 



BINARY 
INPUT 



BCD 
OUTPUT 
A' 



n 'S - 








A o 

A , 

A , 

A 3 o> 
in 

B o S 
B, 

B 2 

B, 
3 K A K 




B f 
c Ve> 






n „ . 


c ^t 




» 
1 


I 

I 


D 1 » 




D 3 , 








" ■> 






D 3 . 




< 


I 


B 


v '/2MC14001 
D N ..... 









CONTROL 




MC14519 OUTPUTS 




BCD OUTPUTS 


n' 


K A 


K B 


D o 


D. 


D * 


D 3 


B' 


C 


D' E 
































1 


1 





A o 


A , 


A 2 


A , 


1 








2 


1 







" 









1 





3 


1 





" 








1 


1 





4 





1 


B 


B , 


B , 


B ! 








1 


5 


1 


1 


v*. 


VB, 


V"i 8 


3 bB 3 








1 


6 


1 


1 




" 


" 


" 


1 





1 


7 


1 


1 






" 


" 





1 


t 



4-BIT BINARY TO 5-BIT BCD— Converts binary 
number within machine to BCD value from to 
15, for driving visual displays. Requires only 
quad two-channel data selector with EXCLU- 
SIVE-NOR function, available in IC packages. 



Article gives truth tables and traces operation 
step by step. — J. Bames and J. Tonn, Binary-to- 
BCD Converter Implements Simple Algorithm, 
EON Magazine, Jan. 5, 1975, p 56, 57, and 59. 




PULSE HEIGHT TO TIME— Simple opamp cir- 
cuit produces time interval proportional to 
height of positive input pulse. Opamp is con- 
nected as integrator whose output is held at 
about zero by negative feedback through D 3 . 
Positive input pulse charges C, and C2, amplifier 
output steps down, and D 3 is reverse-biased. 
Time for output to charge back up to zero, as 
observed on oscilloscope, is then directly pro- 
portional to input pulse height. Article gives de- 
sign equations.— G. B. Clayton, Experiments 
with Operational Amplifiers, Wireless World, 
Sept. 1973, p 447-448. 



^ (MSB) 



J, (LSB) 
BIT 10 O-^ *- 



-TLTL 



-10V 



•/.(Vs.) 



V c ,0- 



Vi (V 8S ) 



+ 15V O • \/)ft ,f 

Vpp |v DD Sk |v F 

14 15 



-FULL-SCALE f TRIM 



MO AC 

(AD7520) 




TIMER 

(Vi AD556) 



14 T ' MER 12 
(Vi AD556) 1Z 



10 






_I_C 3 

*T* 0.Q1 hF 



Tel ± 

•po.OlnF 



16 

3 
Ol 


O NOT USED 


T, 


^. 


ov 

r 




1 °* 




'2r 


i 3799 





-^•o-ifirLrLr 



•10V 



%(Vssl 



-O V c 



Vi <V„) 



DIGITAL TO FREQUENCY — Combination of not critical. Output frequency of each timer de- MDACs Open Up a New Work) of Digital-Con- 

multiplying DAC and 556 dual timer provides pends on supply voltages, capacitor values, and trol Applications, EMI Magazine, Sept. 20, 

complementary output frequencies under con- setting of R,. — J. Wilson and J. Whitmore, 1978, p 97-105. 
trol of digital input. Opamp and diode types are 



214 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Puo 




VOLTAGE TO PULSE DURATION— Optical Elec- 
tronics 9829 opamps are used as fast compar- 
ators and 9718 FET opamp as fast integrator to 
give high precision at high speed for converting 
analog voltage to pulse duration for such appli- 
cations as AD conversion, delta code genera- 
tion, motor speed control, and pulse-duration 
modulation. Output pulse durations can be as 
short as 1 (is. Conversion linearity is better than 
0,1%. Minimum pulse duration is 100 ns, and 
maximum dynamic range is 40 dB. Reference 
voltages are determined by X input; if X is 3 V, 
reference voltages differ by 6 V. Two 9829 
opamps present reference voltages to two com- 
parator opamps. Fifth 9829 sums comparator 
outputs and gives positive output. — "Voltage 
to Pulse Width Converter," Optical Electronics, 
Tucson, AZ, Application Tip 10230. 



VOLTAGE TO CURRENT— Circuit is capable of 
supplying constant alternating current up to 1 
A to variable load. Actual value of load current 
is determined by input voltage, values of Rt-Rj, 
and value of R 5 . Input of 250 mV gives 0.5 A 
through load (RMS values) with less than 0.5% 
total harmonic distortion. Applications include 
control of electromagnet current. — "Audio 
Handbook," National Semiconductor, Santa 
Clara, CA, 1977, p 4-21-4-28. 



VlNCH 



R t = R 2 

R3 = «4 + R5 




+5V 
4 13 



WAVE ■ 
INPUT ' 



-VW 1 

2k 
WW 1 



-)h 



")|- 



100k 
■VW- 

100k 
-iW- 




R ,SR,< R,S R,< R.<R« 



1 > '2> "3> M 4 



SIM74L93 



+5V| 
14 
12 1 



, > > R iaS R » 5 R » 5 ^R 6 <Ry 



SN7405 



11 9 



T 



141 



SN7495 



T 



SN7495 



T 




SN7495 



T 



r 



SINE WAVE 
OUTPUT 



R, 


,R„ 




= 10k 


R, 


R 6 , R 9 , R 13 


= 14.1k 


R 7 


, R ; , R |0 


,R, 7 


- 10.82k 


R, 


R S .R«.R,. 


= 26.1k 



SQUARE TO SINE— Transversal digital filter 
suppresses harmonics present on input square 
wave, to give pure sine wave. Resistors weight 
data as it passes through 1 6-bit shift register, so 
sine wave is sampled at 16 times its frequency 
and theoretically has no harmonics below the 



16th. Simple RC filter removes remaining har- 
monics. Input is clock whose repetition rate is 
16 times desired frequency. SN74L93 4-b'rt rip- 
ple counter divides this down to provide square 
wave of desired frequency. Square wave is sam- 
pled 16 times per cycle and shifted down 



SN7495 16-bit shift register. C, and C 2 are se- 
lected to eliminate higher harmonics. Sine- 
wave output has harmonic distortion of less 
than -50 dB. — L. J. Mandell, Sine-Wave Syn- 
thesizer Has Low Harmonic Distortion, EON 
Magazine, Aug. 15, 1972, p 52. 



CONVERTER CIRCUITS-GENERAL 



215 



SEVEN SEGMENT 
INPUTS • 
FROM 
DRIVER 
COLLECTORS 




BINARY OR 
BCD WORO 
OUT , 



7-SEGMENT TO BCD — Arrangement uses 
SN7448 BCD to 7-segment decoder IC, as 
lookup table for Inverse decoding technique. 
When desired 7-segment code is applied to 
input of decoder and does not match output 
code from IC„ gate IC 3 output is logic 1 . This al- 
lows pulses from clock to advance BCD counter 
IC 5 until its decoded state from IC, matches that 
of input code. With coincidence, output of IC, 
goes low, holding proper BCD code in IC 5 and 
indicating by means of IC*,, that BCD informa- 
tion is ready. With 100-kHz clock, correct code 
is available for at least 90% of digit display 
time. — J. P. Cater, 7-Segment to BCD Decoder, 
EDN Magazine, Feb. 20, 1973, p 92-93. 



Ill 

o- 



lOkii 

V| O WW 

CURRENT OR 
VOLTAGE INPUT 




005/jF 
1N914 




100k 

!!> -15V +15V 



OUTPUT 




5.1ki2 




OlpF 



T 12kS2 



5kS2 




RM4151 
VFC 




SCALE 
FACTOR 



-15V 



T 




6.8ki> 



^1 * 



5.1kS2 
-AM » +15V 



•POLARITY DETERMINED BY DESIRED LED RESPONSE; 
I.E., LED ON FOR DATA HIGH, OR LED HIGH FOR DATA LOW. 



OPTICALLY COUPLED V/F— Input voltage range earity by RM4151 converter used in combina- LED driver.— "Linear Integrated Circuit Data 
of 0-10 V is converted to proportional fre- tion with RC3403A quad opamp that provides Book," Raytheon Semiconductor Division, 
quehcy at output of optoisolator with high lin- functions of inverter, integrator, regulator, and Mountain View, CA, 1978, p 7-40-7-41. 



216 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



COMPARISON 
THRESHOLD 
VOLTAGE 




DIFFERENTIAL TO ABSOLUTE VALUE— Used in 
comparing differential level to threshold level 
with good common-mode rejection. Input 
impedance is maintained high to avoid over- 
loading differential input. Output voltage re- 
mains positive when input polarity is re- 
versed. — R. L. Wiker, Differential to Absolute 
Value Converter, £££Mapsz//ie, Jan. 1971, p 65. 



RMS TO DC — Single AD534 analog multiplier 
and two opamps compute RMS value of input 
signal as square root of sum of squares. Input 
is first squared at X 2 and Y„ then time-averaged 
by integrator. Closing output loop back to X, 
and Y 2 completes square-rooting function. 
Crest factors up to 10 do not appreciably affect 
accuracy as long as input limits of multiplier are 
not exceeded. Accuracy is maintained up to 100 
kHz. Article gives calibration procedure. — R. 
Frantz, Analog Multipliers — New IC Versions 
Manipulate Real-World Phenomena with Ease, 
EDN Magazine, Sept. 5, 1977, p 125-129. 



INPUT 

5V RMS F.S. 

♦10VPEAK 



10 «F 
NONPOLAR 



AC/RMS O M ODE 
[SWITCH 



20k 



o-j If— f- 

S + DcA^ 10k 



O +15V 



10k 



6-isv 



20k 



MATCHED TO 0.026% 

— iW— f-AV-i 

10k „ | 10k 



LT 




S4tr 



5k I 



SOLID TANTALUM 

Hfvo-^ — 




*- j/OUTPUT 

,om| V°to + sv 

-VVV O 

ZERO + 15V 
ADJUST 



O vW f 

Ri 



T 



-If- 



1.2 uF MVLAR 




TO NEGATIVE 

CURRENT SOURCE 

(i ref .200 F A) 



3N138 



10k J OFFSET ADJ. 



330 uf • 



-H- 

1N3605 



«_rw> I 



820 



820 K H 



-0+6V 



►5.1k 




2N3702 i— •— I 2N3702 



3.3k 



.9.1k 



>1.6k 



3.9 mH 



1„F 



S^IOO^F 



a a. 



1 
i-d p- 

2 

Fch 

mL9923 



fa 




ANALOG TO PULSE WIDTH— Stripped-down 
version of dual-slope A/D converter integrates 
input current constantly but switches reference 
current into integrator each time clock pulse 
occurs. Accuracy of 0.1% makes circuit suitable 



for use in digital voltmeter. Reference current is 
switched out of integrator when output voltage 
reaches +4.5V. With values shown, using 100 
kilohms for R v maximum input current is 80 pA 
and full-scale voltage is 8 V. Article includes tim- 



— I 0.2s = T (- 
ing diagram and design equations. — N. A. 
Robin, Analog-to-Pulse-Width Converter Yields 
0.1% Accuracy, EDN Magazine, Nov. 1, 1970, p 
42-43. 



CONVERTER CIRCUITS-GENERAL 



217 




<£ — jjfa-o—Y 



11 — :ioi/F 



CHARGE-DISPENSING V/F CONVERSION— 
Output state of opamp switches C 1 between ref- 
erence voltage provided by diode bridge and its 
inverting input. Network R 2 -C 2 reinforces direc- 
tion of opamp output change. Circuit can deliver 



0-10 kHz output with 0.01% linearity for 0-10 
V input.. — J. Williams, Low-Cost, Linear A/D 
Conversion Uses Single-Slope Techniques, 
EDN Magazine, Aug. 5, 1978, p 101-104. 



OUTPUT 
ENABLE 
ACTIVE 







LO 


W 




BCD OUTPUTS 






v cc C C! 


i 


TV 2j» 2 


2* i 


|16 


15 


14 

71 




13 


12 


11 


10 


9 










b 

DM 76L25 












1 


2 


3 




4 


5 


6 


7 |8 




a 




b 


c 




d 


e 


f 


9 







GNO 



7-SEGMENT INPUTS 



BCD FROM 7-SEGMENT DISPLAY— Single Na- 
tional DM76L25 read-only memory provides 
conversion from 7-segment outputs of MOS 
chip driving display to BCD inputs for data pro- 
cessing. Typical power dissipation is 75 mW. 
Access time is 70 ns when using 5-V supply. 
Article gives truth tablefor all standard and spe- 
cial characters of 7-segment display. — U. Priel, 
7-Segment-to-BCD Converter: The Last Word?, 
EDN Magazine, Aug. 20, 1974, p 94-95. 



Q+15V 



'4 



3-1 /3k 



C 7 



" It"" I 

0.1 i/F _L 



r 





■wv>- 




A 3 
322 



*— o 



R,.C t , R,& R b ARE STABLE 
LOW TC COMPONENTS 



1,-lmA 

t, - R,C,-50»SEC 

R - 20k 



6-1 5V 



VOLTAGE-TO-FREQUENCY USING IC TIM- 
ERS— Two 322 IC timers and single 301A 
opamp provide all functions required for 
charge-balancing type of voltage-to-frequency 
converter, including integrator, level sensor or 
comparator, precision mono, and gated current 



source. Circuit accepts control voltage inputs of 
to -10 V, corresponding to output pulse 
stream range of to 10 kHz. Article describes 
operation in detail. R< should be 4.7 megohms. 
Output pulses of comparator A? trigger mono 
A 3 , which generates pulse having duration t, 



-iooov c 

that saturates Q„ to force reference current l 2 
into summing point of opamp integrator. — W. 
G. Jung, Take a Fresh Look at New IC Timer Ap- 
plications, EDN Magazine, March 20, 1977, p 
127-135. 



218 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



760 
- O-WVWvV*- 

V |N (0- 1V) 500 

+ O vW- 

1.25 k 




0.01fF 



IN914 

-M- 



+ 15V 

1 



TH 



IN914 



2.7k 
•R, 



555 



DCHp 

-^ r OUT 

OUT (OPEN 
COLLECTOR) 



0.022;* F 



; 



2V 



r, IN , -'2 W REF 



V/F GIVES 10 to 10,000 Hz— Current propor- 
tional to input voltage is balanced via periodic 
charging of C, to precisely repeatable voltage by 
opamp A, and FET Q,. With values shown, nom- 
inal scale factor is 10 kHz/V. Input of to 1 V 
gives output of 10 to 1 0,000 Hz with better than 
0.05% linearity. Article gives operating details 
and design equations. — W. S. Woodward, Sim- 
ple 10 kHz V/F Features Differential Inputs, EDN 
Magazine, Oct. 20, 1974, p 86. 



0-10 VDC TO 0-10kHz— Single-supply voltage- 
to-frequency converter produces square-wave 
output at frequency varying linearly with input 
voltage. Linearity error is typically only 1%. For 
values shown, response time for step change of 
input f rom to +10 V is 135 ms. Uses Raytheon 
4151 converter. Supply can be 15 V. — "Linear 
Integrated Circuit Data Book," Raytheon Semi- 
conductor Division, Mountain View, CA, 1978, 
p 7-38. 



100 kn 

v iO-vw- 

VOLTAGE 
INPUT 




DESIGN EQUATIONS 

f n - KV, Where K = 0.466 



W,80.0< + > 



*»„( + 



w K ,W 



;^g>-- 



w».« i + > 



Sign (+) 



i^B^z 



' y~U^W~, Z 




0-360° to 0-180° — Used for converting angular 
information in 360° wrap-around code to ± 180° 
sign-plus-magnitude code. For values under 
180°, converter outputs and inputs are identical. 
For larger input angles, output code is comple- 
ment of input plus one. Used for interfacing 
shaft encoders and synchro-to-digital convert- 
ers to digital display. Article gives truth table 
showing which lines are high and which are low 
at input and at output for angular increments of 
22.5°. — J. N. Phillips, Convert Wrap-Around 
Code to Sign-Plus-Magnitude, EDN Magazine, 
Jan. 5, 1973, p 103. 



CHAPTER 20 

Converter Circuits — Radio 



Various combinations of RF oscillator and mixer circuits convert wide range of 
incoming long-wave and shortwave signals to correct input or intermediate 
frequencies for broadcast or communication receivers not originally covering 
those bands. 



120-150 MHz FOR TRANSISTOR RADIO— Val- 
ues shown cover bands for aircraft radio, 2-m 
amateur radio band, and other services. Circuit 
is regenerative converter, with incoming signal 
tuned by L1-C2 and mixed in 2N2222 or equiv- 
alent transistor connected as oscillator with fre- 
quency controlled by L3 and C7. Difference fre- 
quency is adjusted to fall in standard broadcast 
band, for pickup by radio when converter is 
mounted close to ferrfte loop. For local stations, 
antenna of converter can be 19-in length of wire. 
L2 and L4 are 100-/iH chokes or about 20 in of 
fine wire wound on 100K resistor. — S. Kelly, 
Simple VHF Monitor, 73 Magazine, July 1976, 
p160. 



lOpF 



r^H 



L4 IK 





[V— T"f 



5.5 MHz 

INPUT 

FROM 

28 MHz 

CONVERTER 



IN400I 



AGC-MGC FROM 
"° l-F AMPLIFIER 




3A* CONT 



5.5 MHz TO 455 kHz-Developed for use as sec- followed by triple-tuned filter feeding second of receiver.-D. M. Eisenberg Build This All- 

ond converter in all-band double-conversion mixer Q24, with Q25 as crystal oscillator. Sup- Band VHF Receiver, 73 Magazine, Jan 1975 p 

superheterodyne receiver for AM. narrow-band ply is 13.6 V regulated. Article gives all circuits 105-112. 
FM, CW, and SSB operation. IF amplifier 023 is 



219 



220 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



r 1 ^ 



LZ 1000 RFAMP 



D-DC V 
O-pn-pk 



EXCEPT AS INDICATED, DECIMAL 
VALUES OF CAPACITANCE ARE 
IN MICROFARADS I JiF I ; OTHERS 
ARE IN PICOFARADS (pF OR jiJiFl 
RESISTANCES ARE IN OHMS; 
k -1000. M> 1 000 000 






CI -C2 


C3 


LI 


L2-L3 


L4 


10 MHz 


90 pF 


■22V? 


2-1/2 turns 
No. 24 enamel 
over L.2. 


Same as L5* 


Same as L5* 


15 MHz 


43 pF 


300 pF 


1-1/2 turns 
No. 24 enamel 
over L2- 


Same as L5* 


5.5 mH (nom.) 
Miller 46A566CPC 


25 MHz 


22 pF 


48 pF 


1-1/2 turns 
No. 24 enamel 
over L2 


1.8 pH (nom.l 
Miller 46A186CPC 


Same as L5* 



WWV CONVERTER— Designed for use with am- 
ateur receiver for reception of NBS stations 
WWV or WWVH on 10, 15. or 25 MHz. Receiver 
is tuned to 4, 14, or 21 MHz to serve as IF am- 
plifier, detector, and audio stages. Current drain 
of converter is 15 mA, low enough for operation 
from 9-V transistor-radio battery. Table gives 
tuned-circuit values for frequency desired. Re- 
striction to single frequency eliminates band- 
switching. Q1 can be any common-gate JFET RF 
amplifier providing 8-dB gain. Mixer is 40673 
MOSFET. Oscillator transistor is not critical. Os- 
cillator output serves for all three WWV fre- 
quencies. — C. Watts, NBS — Ears for Your Ham- 
Band Receivers, OST, June 1976, p 25-26. 



*L5 - 2.42-2.96 fiH, Miller 46A276CPC 



'LONG ANT. 
'Z3'-I45' 




EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS 1 JjF I ; 
OTHERS ARE IN PICOFARADS ( pF OR JJJlF); 
RESISTANCES ARE IN OHMS ', 
k. 1000, M-I000 000. 




C6 — Silver mica 3900 pF, 5-percent. 

C9 - Trimmer, 50 to 380 pF (Arco No. 465). 

L1 - Slug-tuned inductor (J. W. Miller No. 9004). 

L2 - Slug-tuned inductor (J. W. Miller No. 9006). 

L3, L4 — Ferrite-antenna coil (J. W. Miller No. 

6300). 
L5 — 2 turns of No. 26 enam. wire on cold end of 

L2. 
Y1, Y2 - HC-6/U type holder. (International 

Crystal Co.) 



175 kHz TO 1515 OR 3515 kHz— Crystal-con- 
trolled VLF converter covering 1750-meter band 
gives choice of two outputs, selected by S2, for 



communication or broadcast receiver. Tuning 
range is 160 to 190 kHz. Connect general-cov- 
erage receiver to IF output terminals with 



length of coax. — J. V. Hagan, A Crystal-Con- 
trolled Converter and Simple Transmitter for 
1750-Meter Operation, QST, Jan. 1974, p 19-22. 



CONVERTER C I R C U I T S — R A D I O 



221 




MPF-102 50pF 
MIXER 



1^ . T" 3 ° i \ ^ QpF 




C11 — Two 1/2-inch pieces. No. 18 insulated 

hookup wire, twisted together 1/2 turn. 
L1 . L2, L3 — 18 turns No. 28 enam. wound on 

Amidon T-30-6 core. LI tapped at 6 turns and 

1 1 turns from ground end. 
L4, L5 — 5 turns No. 20 enam., formed by using 

threads of 1 /4-20 bolt as a guide. L5 is tapped 2 

turns from the ground end. 



28MHj 



L6 — 10 turns No. 24 enam. close wound on the 

body of a 1000-ohm 1/2-watt resistor. 
L7, L8 — 5 turns No. 20 enam., formed the same 

as L4. Both are tapped 2 turns from the hot 

end. 
Y1 - 58.225-MHz crystal. International Crystal 

third-overtone type in FM-1 (wire leads) or 

FM-2 (pins) holder. 



TO 144 MHz — Addition of small upcon- 
verter to 144-MHz (2-meter) SSB transceiver 
permits reception of 10-meter signals from 
Oscar satellite on single transceiver. Output of 



mixer, between 145.85 and 145.95 MHz, is fed 
to antenna terminal of receiver. — T. McMullen, 
An Up Converter for Oscar Reception, QST, 
March 1975, p 41-44. 



152-165 MHz TO 146.94 MHz— Permits listen- 
ing to public service band with any good 2- 
meter FM receiver or transceiver. Local oscilla- 
tor has tuning range of 7-8 MHz and uses ger- 
manium PNP high-frequency transistor. No RF 
stage is needed for full quieting from stations 
10 miles away when using ground-plane an- 
tenna. To avoid burning out converter, do not 
transmit while converter is connected to trans- 
ceiver. Article gives coil-winding data. — H. 
Schoenbach, Public Service Band Converter, 73 
Magazine, Dec. 1974, p 78-79. 



68 
S.M. 



FL1 
1.8-1.9MHZ 



•» (o ) I | ( If f f— )(-» . ei-lr-i 



_§8_ rf AMPLIFIER 

S.M. 



DOUBLY 

BALANCED 

MIXER 



2N5486 ,5 1.8-2.0 MHz 



■M2VO 



14.0-14.2 MHz 

L5 _ l-F 

OUTPUT 




EXCEPT AS INDICATED, DECIMAL 
VALUES OF CAPACITANCE ARE 
IN MICROFARADS t JjF ); OTHERS 
ARE IN PICOFARADS (pF OR jiJ>F); 
RESISTANCES ARE IN OHMS; 
k -1000. M>1 000 000 



SILVER MICA 



BOTTOM 
VIEW 



160-METER CONVERTER— Designed for use 
with receiver covering 20-meter band. Uses up- 
con version techniques to get from 1.8 MHz of 
160-meter band to 14-MHz tunable IF of re- 
ceiver. Butterworth bandpass filter at input of 
converter covers 1.8-1.9 MHz. L1 and L2 each 



have 31 turns No. 22 enamel on T68-6 toroid 
core to give 5.1 /uH. L3 is 50 jiH, using 66 turns 
No. 18 enamel on T68-1 toroid. Other three coils 
each use T50-6 toroid core, with L4 having 7 
turns No. 24 enamel, L5 1 1 turns No. 24 enamel. 



and L6 26 turns No. 28 enamel. U1 is SRA-1, CM- 
1, or ML-1 diode-quad double-balanced mixer 
module. — M. Arnold and D. DeMaw, Build This 
High-Performance Top-Band Converter, QST, 
Oct. 1978, p 22-24 and 38. 



222 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



| 2 ' 7 ' 50 l ST-™*' 



Hf— ft) OUTPUT 

7r % 




2-METER FOR 10-MHz IF — Designed for ex- tuned circuits at input frequency give overall Converter uses grounded-gate FET circuit. — U. 
treme linearity and selectivity while keeping bandwidth of 4 MHz, with image suppression of Rohde, High Dynamic Range Two-Meter Con- 
noise figure below 5 dB. Circuit has +15 dBm 60 dB for 10-MHz IF and 80 dB for 30-MHz IF. verter. Ham Radio, July 1977, p 55-57. 
intercept point and 16-dB power gain. Five 



MIXER 

40673 (3NI4I) 




144 MHz TO 28 MHz— Brings 2-meter band to 
input range of ordinary amateur receiver. Crys- 
tal eliminates need for multiplier stages that 
can generate spurious responses. Signal can be 
injected from external source if crystal is re- 
moved. — Construction Hints for VHF Convert- 
ers, QST, Sept. 1975, p 32-33 and 39. 



C1-C4, incl. - 10-pF tubular ceramic trimmer (Centralab 829-10). 

L1 - 6 turns No. 16, 3/8-inch dia, spaced wire dia. Tap at 2-1/2 turns 

from bypassed end, or for best noise figure. 
L2 - 4-3/4 turns, like L1 . 

L3 - 4 turns No. 22, 1/4-inch dia, 5/16 inch long. 
L4 - 2.7 to 4.2-(jH slug-tuned coil (Miller 4307). 
R1 — Adjust for 5 mA drain current, or lowest noise figure. Final value 

in original unit, 220 ohms. 
Y1 — 116-MHz overtone crystal (International Crystal Mfg. Co.). 



CONVERTER C I R C U I T S — R A D I O 



223 




L1.L2 
L3 



magnetically tuned inductor (see text) 
10 turns no. 20 on 'A" (6-mm) slug- 
tuned form, tapped 5 turns from cold 
end 
2 turns no. 20 around cold end of L3 



100-300 kHz 
LOW-PASS FILTER 



20 on "A" (6-mm) slug- 



15 turns no. 
tuned form 

4 turns no. 20, center tapped, around 

cold end of L5 

2 turns no. 20 around cold end of ' s 



TUNABLE VLF— Gives tuning range of 1 kHz to 
150 kHz without bandswftching, for WWV 
transmissions on 20 and 60 kHz and for opera- 
tion on no-license amateur band around 1750 
meters. Uses inductive tuning with toroidal fer- 
rite core L1-L2 that is magnetically biased by 
pair of Vinch diameter button-type permanent 
magnets. Rotating one of magnets with respect 
to other varies flux through toroid, changing its 
permeability and inductance. Toroid uses 100 
turns of stranded wire to give inductance vari- 
ation from 100 iM to 12 mJH (120:1 range). Fer- 
rite cores with higher permeability require 
fewer turns. Converter output on 15 meters 
feeds into communication receiver. Local oscil- 
lator uses FT-243 7-MHz crystal in third-over- 
tone mode to give 21 MHz. Antenna is directly 
coupled or coupled through capacitor to im- 
prove matching to long antenna. — G. Ruehr, 
Tuned Very Low-Frequency Converter, Ham 
Radio, Nov. 1974, p 49-51 . 



POST-MIXER 
AMPLIFIER 



, 18-2. 0MH« 

^ T5 




+12V 

H1-L3, incl. - 40 turns no. 30 enam. wire 

wound on a T50-3 core. 
U4 — 17 turns no. 28 enam. wire wound on 

a T50-2 core. 



100-200 kHz TO 1.8-2 MHz— High-perfor- 
mancu low-frequency converter picks up exper- 
imental CW, SSB, RTTY, and beacon signals in 
160-190 kHz band for conversion to tunable IF 
range of modern communication receiver. Dou- 
ble-be lanced diode-ring mixer has conversion 



EXCEPT AS INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS ( jiF I ; 
OTHERS ARE IN PICOFARADS ( pF OR jijjF); 
RESISTANCES ARE IN OHMS ; 
k= 1000, M'1000 000. 



L5 — 70 turns no. 30 enam. wire wound on 
a T50-2 core. 

T1 , T2 — Broadband transformer. For con- 
ventional style winding: primary, 27 
turns no. 30 enam. wire wound over sec- 
ondary turns. Secondary, 54 turns no. 
30 enam. wire wound on an FT-50-43 
core. For trifilar winding: three 
individual windings of no. 30 enam. wire 



loss of 6-8 dB and will stand up against strong 
signals without causing overloading and cross- 
modulation. Use 1N914 matched diodes. Di- 
plexer at mixer output is tuned to 3 times 



on an FT-50-43 core. Connect as shown 

in inset drawing. 
T3 — Broadband transformer. Primary, 50 

turns no. 30 enam. wire on an FT-50-72 

core. Secondary, 7 turns no. 28 enam. 

wire wound over primary turns. 
Y1 - General-purpose crystal. 1700 kHz, 32- 

pF load capacitance. 



converter IF. Article covers construction and 
alignment. — D. DeMaw, A High-Performance 
Low-Frequency Converter, GST, June 1977, p 
23-26. 



224 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



PASSIVE LONGWAVE— Uses VFO of amateur- 
band transmitter to supply heterodyne for 
bringing in frequencies below 450-kHz broad- 
cast band on amateur receiver, such as Omega 
navigation station on 10.2-13.6 kHz, NAA Tele- 
type on 17.8 kHz, and GBR time signals on 16 
kHz. L,-C,-C 2 100-kHz input wavetrap for loran 
C can be omitted at far-inland locations. C 2 is 
two-gang broadcast variable capacitor with 
both sections in parallel. Mount L 2 at right angle 
to L 3 . Converter should be well shielded. Oper- 
ation involves tuning receiver to bottom of any 
amateur radio band, on frequency equal to dif- 
ference between VFO and that to which receiver 
is tuned. If VFO is on 7 MHz and receiver is tuned 
to 7.08S MHz, combination will be set for 85-kHz 
station. In USA, unlicensed transmission on 
160-190 kHz is permitted with 1-W input and 
50-foot antenna including length of transmis- 
sion line. — M. Muench, Longwave Simplified, 
CO, March 1976, p 41-42. 



To transmitter 



To VFO 





VFO CONVERTER— Used in solid-state five- 
band communication receiver. VFO input (5-5.5 
MHz) goes directly to amplifiers Q5 and Qfi 
when bandswitch is on 3.5 or 14 MHz. When 
VFO signal is applied to balanced mixer CR7- 
CR10, product is at 9 MHz. Diodes should be 
carefully selected for equal voltage drops ±20 
mV at various current values such as 0.75, 2, 10, 
and 20 mA. When bandswitch is on 7, 21, or 28 
MHz, VFO signal is mixed with output of FET 
crystal oscillator and filtered before being ap- 
plied to Q5 and Q6. FET oscillators Q1-Q4 are 
energized by +12 V from bandswitch, with 
diodes CR1-CR4 selecting output. Crystals are 
parallel-resonant with 32-pF load. Y2, Y3, and 
Y4 are third-overtone type. — P. Moroni, Solid- 
State Communications Receiver, Ham Radio, 
Oct. 1975, p 32-41. 



CR1-CR6 1N914 or equivalent 

CR7-CR10 selected 1N270 diodes (see text) 
CR11-CR17 1N914 or equivalent 



L1-L4 



L5.L6 

L7-L10 
Tl, T2 



0.6 MH (10 turns no. 22 
(0.6mm) enamelled on 3/8" 
(9mm) diameter slug-tuned 
forms. Link is 3 turns no. 22 
(0.6mm) 

1.2 MH. 20 turns no. 28 
(0.3mm) on 3/4" (9mm) diam- 
eter slug-tuned forms 
0.6 /KH (same as LI - L4) 
10 turns no. 32 (0.2mm), trifilar 
wound on Amidon T50-6 toroid 
core 

10 turns no. 32 (0.2mm), trifilar 
wound on Amidon T50-6 toroid 
core. Collector winding has two 
windings in series to give 2:1 
ratio 



CONVERTER C I R C U I T S — R A D I O 



225 



HIF 



3.5 MHz CRYSTAL 



.001 



^ 



Be LOOPSTICK 



J 



HEP5I 
PNP 



TO OUTSIDE 
WIRE ANTENNA 



■t 



SHORT PIECE OF 
COAX TO RECEIVER 
TERMINALS 



v* 



-1, 



25-500 kHz TO 3.5-4 MHz— When receiver is 
tuned to 3.5 MHz and converter is peaked for 
loudest signal, combination is tuning 25-kHz 
range. With receiver tuned to 4 MHz, converter 
gives coverage at 500 kHz.— Circuits, 73 Mag- 
azine, May 1977, p 19. 



20 METERS TO 40 METERS— Used with 40- 
meter receiver for which circuit is also given. 
Converter output is in 40-meter band, for direct 
feed to input of receiver. L4 is 12 turns No. 26 
enamel on Amidon FT37-61 toroid, L5 is 24 turns 
No. 26 enamel on Amidon T-50-6 toroid, and T3 
uses Amidon T-50-6 toroid with 2 turns No. 26 
enamel for primary and 21 turns for second- 
ary.— D. DeMaw, The Mini-Miser's Dream Re- 
ceiver, QST, Sept. 1976, p 20-23. 




SM.- SILVER MICA 
O-PK-PkV Q"] 



■0-M3V 



•*-5" OF RG 174/U 



SECONDARY: 
10 T. no. 24 
FORUVAR 

f ' TO B.C. 

Q V RECEIVER 




L-l 61 - 122 MH (Cambion X2060-7) 

L-2 10 - 18 mH (Cambion X2060-4) 

L3 2 - 3.7 pH (Cambion X2060-1) 

L-4 1.3 - 2.5 M H (Delevan 4000-12) 



L5 0.83 - 1.6 HH (Delevan 4000-10) 

L6 2 8- 63 mH (Cambion X2060-6), 10 turn secondary 

Q1.Q2 3N140, MFE3006, HEP F2004, RCA 40673 

Q3 MPF102, HEP802, HEP F0015 



WWV FET CONVERTER— Receives WWV on 
2.5. 5, 10, 15, and 20 MHz, using modified tran- 
sistor AM broadcast receiver operating 
straight-through for 2.5-MHz reception and 
serving as IF amplifier for converter when tuned 
to higher WWV and WWVH frequencies. Only 



two crystals are needed because each allows 
reception of two WWV frequencies; thus, 10 
and 20 MHz are image frequencies when receiv- 
ing 5 and 15 MHz. Loopstick antenna of radio is 
replaced with small slug-tuned coil L6 to use 
2.5-MHz image frequency when radio is tuned 



to 1590 kHz. Converter uses dual-gate MOS- 
FETs in RF stage Q1 and mixer 02, with JFET Q3 
as oscillator. Antenna is short piece of wire. — 
H. Olson, Five-Frequency Receiver for WWV, 
Ham Radio, July 1976, p 36-38. 



226 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



ft/0 

'VW 0+I2V 

100 




SINGLE-CRYSTAL FOR 46 TO 420 MHz— Covers 
all VHF amateur bands by using mixer-gener- 
ated harmonics of 66-MHz crystal oscillator fre- 
quency for mixing action. IF can be tuned with 
any communication receiver. Fundamental is 
used directly, third harmonic of 138 MHz serves 
for 2 meters, fifth of 230 MHz for 220-MHz band, 
and ninth of 414 MHz for 420-MHz band. Q1-Q3 
are broadband RF preamp. Y1 is plated overtone 
crystal oscillating at 46 MHz in series-resonant 
mode. Q5 and Q6 form differential-amplifier os- 
cillator, and Q4 is mixer driver. No tuning is re- 
quired in converter, but external tuning is re- 
quired to prevent device from working on all 
bands at once. All transistors are part of RCA 
CA3049T IC, for which pin numbers are circled. 
LI is 72 inches of No. 30 enamel, doubled and 
twisted 1 turn per inch and wound on 1-meg- 
ohm 1 A-W resistor to form quarter-wave trans- 
mission line. — S. Smith, Four-Band VHF Receiv- 
ing Converter, Ham Radio, Oct. 1976, p 64-66. 



105.625 MHz 



211.25 MHi 
L13 



52.8125 MHI 




C1 , C2 — Nut or copper disk on end of adjusting 

screw, with lock nut on top side of assembly. 

Makes variable capacitance to midpoint of 

half-wave trough-line inner conductor. 
C3 — 0.5- to 5-pF glass trimmer. 
C4, C5 — 1 2-pF ceramic trimmer. 
L1 —2 turns insulated hookup wire around L2. 
L2.L3 - 13 turns No. 28 enam, 1/2 inch (13 mm) 

iron-slug form. 
IL4 — L-shaped coupling loop, 3/4 inch (19 mm) 

long, No. 18, adjacent to L5. 
L5 L6 - 1/4-inch (6 mm) copper tubing, 4-1/4 

inches (1 14 mm) long. 
L7, L8 — U-shaped double coupling loop. No. 14, 

1/2 inch (13 mm) wide, 1/2 inch long, centered 

in opening in partition P5. 



L9 — Like L4, except adjacent to L6. Collector 

lead of Q5 is part of this loop. 
L10, L12, L14 - 1 turn No. 14, 3/8 inch (10 mm) 

dia. 
L1 1 -1-1/4 turns No. 1 4, 3/8 inch dia. 
L13 - 3 turns No. 14, 3/8 inch (10 mm) dia. 
L15 - 5 turns No. 14, 3/8 inch (10 mm) dia. 
L16 — 2 turns insulated hookup wire around L17. 
L17 - 16 turns No. 28 enam, 1/4 inch (6 mm) 

iron-slug form. 
Q5, Q6 — Uhf transistor. Use best available 

low-noise type for Q6. 
R1 , R2 — 10,000-ohm linear -taper control. 
RFC1, RFC2 - Ferrite-bead choke. 
Y1 - Third-overtone crystal, 52.8125 MHz, or to 

suit i-f range used. 



1296 MHz TO 28.5 MHz— Uses UHF transistors 
in active mixer and in final stage of injection 
chain, for lower noise figure and useful conver- 
sion gain. Doubler and tripler stages are individ- 
ually shielded. — L. Crutcher, An Active-Mixer 
Converter for 1296 MHz, QST, Aug. 1974, p 11- 
14. 



CONVERTER C I R C U I T S — R A D I O 



227 




07 '* 

TEXT) TV* 
L _ 



BELOW BROADCAST BAND— Simple solid- 
state converter can be used with any good com- 
munication receiver covering 3.5-4 MHz to 
bring in stations from 5-550 kHz (200 meters 
and up). Input coil L1 is changed from 0.28 H for 
5-11 kHz to 120 /tH for 250-550 kHz in eight 
steps, as given in article. C2 consists of two 3- 
gang variable capacitors with stators wired in 
parallel, gang-tuned with dial cords. Trimmer 
C7 is 1-12 pF, adjusted to give reliable starting 
of FT-243 3500-kHz crystal. L2 is 80-90 /tH for 
80 meters, and loopstick is for broadcast 
band.— K. Cornell, 200 Meters and Up Receiving 
Converter for Low Frequencies, Ham Radio, 
Nov. 1976, p 24-26. 



28-30 MHz T0 1.65 MHz— 10-meter tuner gives 
excellent image suppression with 1.65-MHz 
output, for feeding into inexpensive receiver 
having 1.65-MHz IF. Tuning capacitors are 
three-gang Miller 1460-1. Article gives all coil 
data along with construction details.— B. Hois- 
ington, Tuneable 10 Meter Converter, 73 Mag- 
azine, Jan. 1974, p 57-62. 




ONE SECTION OF MILLER 
!460-l 207 MAX 



432 MHz 
INPUT 
FROM 
BANDSWITCH 



^-n< 



m n 



3 N ^fC 



L22S 2N5485 



177 rb 



DSG 2N5485 
S G D TIS-34 

loool 




CRYSTAL =£ 
50.5 MHz ^ 



47 ° 16 
■*' 2 N 5485 

RFC \ <*> 22 C hF 

.22 M H j -22>.H . 

I 220 220 J 

f vw * === — f . ■ VA 1 I 

IOO0 i FT ^T T^FT ^X , 

X 'ooo^ J^ooo ;£• 



.47 



017 
2N5485 



MOOK 



1000 



018 
TIS-34 



50.5 MHz Jy°i Tl'l-34 202MHz 



3.3K 



L28U 30 
75 J ph 



28 MHz 
OUTPUT TO 
BANDSWITCH 



"1 = 

1.005 



lh f 



>220 



404 MHz 




A* FROM 
BANDSWITCH 



^TJ^uT^mTl^ 9 ^^ "*~? f !L" Se '" a " band doublec °™^°" regulated.Artidegivesallcircuitsof receiver.- 
grounded-grid RF amplifier stages 015-016, superheterodyne receiver for AM, narrow-band D. M Eisenberg Build This All-Band VHF R« 
m,xer 017, and crystal oscillator 018-0,9. De- FM, CW, and SSB operation. Supply is 13.6 V ceiver, ^^e Jan mt p lotm 



228 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



V 



:£>C>C>C>i 



r 



CRYSTAL 
I MHz 

hii — 




TO PIN 14 
* ON 
SN7400N 



8-30 MHz AMATEUR BANDS— Will convert any be almost any general-purpose high-frequency put is amplified and filtered by Q1 to produce 

frequency in tuning range to IF value between transistor. Two of gates in SN7400N TTL IC control voltage for tuning D3. Output from 

3 5 and 4 MHz. Requires only three transistors serve as crystal oscillator, and other two gates mixer 03 is untuned, with RFC as drain load ele- 

and one IC.D1 and D2 can be germanium or sil- are buffers for detector diodes D1 and D2. ment.-R. Megirian, High Frequency Utility 

icon suchas1N914.D3isrectifierdiode.02can Diodes are modulated by VCOQ2. Detector out- Converter, 73 Magazme, June 1977, p 50-53. 




UP/DOWN — Circuit shown was developed for 
use in 5645.8-kHz IF amplifier of Drake R-4B am- 
ateur-band receiver, to utilize high-perfor- 
mance characteristics of Sherwood Engineer- 
ing CF-125/8 CW crystal filter having bandwidth 



of only 125 Hz. Texas Instruments TU42 dou- 
ble-balanced mixers convert IF signal to 5695- 
kHz center frequency of filter and convert filter 
output back to IF value. Same crystal oscillator 
serves for both upconversion and downconver- 



sion. Gives true single-signal reception. Article 
covers procedures for interfacing any crystal fil- 
ter with any receiver IF value. — H. Sartori, An 
Up/Down Filter Converter, Ham Radio, Dec. 
1977, p 20-25. 



CONVERTER CIRCUITS-RADIO 



229 




r t" i 1 i 

*47fc: ^.o, 5,0* 

m m m m ' '■ 



I 



OSS 
2N3B19 
(BOTTOM) 





r 

7 



so Z' I "\ 1 o 




land 


LI 


L2 


L3 


Yl 


40 


20 turns no. 36 (0.13mm), 
2 turn link 


20 turns no. 
36 (0.13mm) 


4.7 ;UH 


11 MHz 


20 


12 turns no. 28 (0.3mm), 
1.5 turn link 


12 turns no. 
28 (0.3mm) 


2.2 /JH 


18 MHz 


15 


7 turns no. 28 (0.3mm), 
1 turn link 


7 turns no. 
28 (0.3mm) 


1.5 MH 


25 MHz 


10 


4 turns no. 28 (0.3mm), 
1 turn link 


4 turns no. 
28 (0.3mm) 


1.5 fiH 


25 MHz 



10-40 METERS TO 3.5-4 MHz— Five-band con- 
verter is designed for use with miniaturized 
communication receiver tuning from 3.5 to 4 
MHz. Signals for 80-meter band are fed directly 
to receiver. Two-gang tuning capacitor used to 
peak converter front end is film-dielectric type 
taken from transistor FM radio.— R. Megirian, 
Design Ideas for Miniature Communications Re- 
ceivers, Ham Radio, April 1976, p 18-25. 



WVW ON AC/DC RADIO— When fed into IF am- 
plifier of ordinary broadcast-band radio, simple 
converter circuit gives choice of WWV on 10 or 
15 MHz, for reception of time signals and radio 
propagation reports. C2 is 1.5-10 pF; C3 and C6 
are 7-60 pF; C4 is 7-100 pF (all compression 
trimmers); and C5 is 1.8-8.7 pF miniature vari- 
able capacitor.— W. C. Powis, Notes on Con- 
verting the AC/DC for WWV, 73 Magazine, Oct. 
1974, p 116. 




GROUNDING POINT 




2 m TO BROADCAST BAND— Permits tuning to 
2-m (146-MHz) amateur band with ordinary AM 
auto radio, for monitoring FM repeaters and 
other 2-m amateur stations. Article stresses im- 
portance of shielding, compartmentalization, 
and RF blocking along power lead to prevent 
bleed-through of broadcast stations. Separate 



9-V battery gives long life if converter is turned 
off when not in use, because drain is only 25 mA. 
L2 is 4 turns No. 20 on 7-mm slug-tuned form, 
with 2-tum link LI at low end and tap Vk turns 
from low end. L3 and L4 are 3 turns No. 20 on 
7-mm slug-tuned form. L5 is 20 turns No. 30 on 
4-mm solid ferrfte form. Yl is 48.5-MHz third- 



overtone crystal. Converter gives good recep- 
tion of both AM and FM stations on 2 m, with 
sharpness of receiver IF tuning determining 
ability of radio to slope-detect FM signals.— J. 
R. Johnson, New Improved Repeater Monitor, 
73 Magazine, Dec. 1976, p 106-109. 



230 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



9-V TRANSISTOR 
RADIO BATTERY 



|-H* (H 




< 10 M 
10 o I OUTPUT 



EXCEPT A3 INDICATED, DECIMAL VALUES OF 
CAPACITANCE ARE IN MICROFARADS ( JjF ) ; 
OTHERS ARE IN PICOFARADS I PF OR l>pf)\ 
RESISTANCES ARE IN OHMS ", 
k = I 000, M= I000 000, 



COILS: {3/8" D slug-tuned form) 

LI 13t No. 38 double-cotton covered win 

L2 2t No. 20 enam. wire, ct (B+ end). 

2t No. 18 insulated hookup wire, ct 

(Gnd end). 

8t No. 20 enam. wire, close wound. 
L5 5V2t No. 20 enam. wire, close wound. 
L6 33t No. 40 double cotton-covered win 
close wound. 



160 METERS T0 10 METERS — Simple converter 
adds 160-meter band capability to older CW or 
AM receiver. Passive mixer is adequate. High 
output frequency eliminates IF feedthrough and 
image signals. Crystal oscillates on third over- 
tone and feeds directly into mixer. — A. Bloom, 
A Simple 160-Meter Converter, QST, Feb. 1975, 
p46. 



144 MHz TO 14 MHz— Oscillator uses 43.333- 
MHz overtone-cut crystal feeding class A tripler 
that infects 130-MHz signal into gate of MPF-102 
mixer for combining with 144-MHz output of 
IGFET RF amplifier to give 14 MHz for amateur- 
band or general-coverage receivers. Article cov- 
ers construction and alignment, including de- 
tailed coil-winding data.— C. Klinert, A Two 
Meter Converter, 73 Magazine, Sept. 1973, p 
65-67. 




2N5I82 
(BOTTOM VIEWS) 



MIXER 

2N Sl8 OR 2N3600 

1.65 MHZ TO 135 KHZ 



OSCILLATOR 
2N3600 
I.T85 MHZ 



-»- 




^ 



# 



ARCO 469 

130- 600 

PF 



1.65 MHz TO 135 kHz— Provides good selectiv- 
ity, good AVC, and smooth tuning. Article gives 
coil-winding data. — B. Hoisington, Miniboxing 
the 432er Receiver, 73 Magazine, Jan. 1975, p 
46-52. 



CONVERTER CIRCUITS-RADIO 



231 



50MHI 
INPUT 
FROM 
BANDSWITCH 



2.2 

*r- 



28MHz 
OUTPUT TO 
BANDSWITCH 



mm 



l o o of 
TIS-34 




CRYSTAL 
22MHz 



$220 ««° S 

f 27 M H 30^H f 

1 rvw\ u ,-w w I 

JL T ~Tft 



r 



A+ FROM 
BANDSWITCH 



r 00 



50 MHz TO 28 MHz-Contains bandpass filter, for use in all-band double-conversion superhet- Article gives all circuits of receiver -D M El 
two grounded-gnd RF amplifier stages Q1-Q2. erodyne receiver for AM. narrowband FM. CW, senberg ZumZ££X%£j!iJ2 73 
m,xer Q3. and crystal oscillator Q4. Developed and SS8 operation. Supply is 13.6 V regulated! Ch T Jan. V 9 75 Tp foX-m 



144 MHz 
INPUT 
FROM 
BANDSWITCH 



28 MHz 
OUTPUT TO 
BANDSWITCH 




A* FROM 
BANDSWITCH 



144 MHzTO 28 MHz-Contains bandpass filter, use in all-band double-conversion superhetero- tide gives all circuits of receiver -D M Eta-n 
grour^ed-grulRFarnp.ifierstagesQS-Qe.rnixer dynereceiverforAM.narrowbandFM.CW.and ^ZZnZZ^t^Zc^er?^' 
Q7. and crystal oscllator Q8-Q9. Developed for SSB operation. Supply is 13.6 V regulated. Ar- J£ Jan 1975 p iTl « " 



220 MHz 

INPUT 

FROM 

BANDSWITCH .82 



CRYSTAL : 
46MHz 



,00K Jr X^oo 



28MHz 
OUTPUT TO 
BANDSWITCH 




A+ FROM 
BANDSWITCH 



30^ H 



£°' i« 



/* /* .sou 

220 MHz^ TO 28 MHz-Contains bandpass filter, veloped for use in all-band double-conversion regulated. Article gives all circuits of receiver - 
grounded-grid RF amplifier stages Q10-Q11, superheterodyne receiver for AM, narrowband ^ tA. B^uZlZZml^^HF^- 
m,xer 012. and crystal oscillator Q13-Q14. De- FM, CW. and SSB operation. Supply is 13.6 V ceiver, J3mJ2£~L!^X^ 



232 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



VEft ANT INPUT 
TEXT! 



VLF CONVERTER— Uses low-pass filter instead 
of usual tuned circuit, so only associated re- 
ceiver need be tuned. Measured threshold sen- 
sitivity is about 20 /*V. Transistors used in dual- 
gate MOSFET mixer and FET oscillator are not 
critical. Crystal can be any frequency compat- 
ible with tuning range of receiver used. With 
3.5-MHz crystal, 3.5 MHz on receiver dial cor- 
responds to kHz and 3.6 MHz to 100 kHz.— R. 
N. Coan, VLF Converter, Ham Radio, July 1976, 
p69. 





) 220-MHJ 
OUTPUT 



©3*1 





COAX RS-174/U OR EQUIVALENT 



28 MHz TO 220 MHz FOR TRANSMIT— Permits 
use of 2-meter transceiver to transmit in 220- 
MHz band with minimum of 6-W power output 
for 1-W drive on 28 MHz. Local-oscillator output 
at 192 MHz can be used for receiving converter 
as well. Use 8-pF butterfly-type air variable 
(Johnson 160-028-001) for C24, C26, C28, and 
C32. D1 is GE ZD8.2 8-V 1-W zener.— F. J. Merry, 
A 220-MHz Transmit Converter, QST, Jan. 1978, 
p 16-20. 



L1 — 12 turns No. 18 wire, 3/4 In. long, 

1/4 in. diameter. Tap at 1-3/4 turns. 
L2 — 6 turns No. 18 wire, 3/4 in. long, 1/4 

in. diameter. Tap at 2 turns. 
L4 — 3 turns No. 18 wire, 3/4 in. long, 1/4 in. 

diameter. Tap at 1 turn. 
L3 — 0.47-mH rf choke (Millert. 
L5 — 1 turn, 1/2-in. dia, 3/4-ln. leads; No. 

22 Insulated wire. 
L6 — 1-1/2 turns, 1/2-in. dia, 1-in. leads; No. 

16 wire. 
L7 — 1-1/2 turns, 5/8-in. dia, 3/16-in. leads; 

No. 16 wire. 
LB — 1/2 turn, 5/8-in. dia, 3/16-in. leads; No. 

16 wire. 
L10 — 1-1/2 turns, 5/8-in. dia, 1-1/4-in. leads; 

No. 16 wire. 
L11 — 1 turn, 1/2-in. dia. 3/4-in. leads; No. 

22 insulated wire. 



CONVERTER C I R C U I T S — R A D I O 



233 



28MHz 
INPUT 
FROM 
BANDSWITCH 




!i L 4 A J + i^'JL 



020 

TIS-34 



5.5 MHz 
OUTPUT TO 

. SECOND 

L34Lf CONVERTER 

270 1 G) 



A+ CONT 




28 MHz TO 5.5 MHz— Contains bandpass filter, 
grounded-grid RF stage Q20, mixer Q21, and 
oscillator Q22, with all tuning accomplished by 
variable-capacitance diodes. Oscillator covers 



22.5 to 24.5 MHz. Used in all-band double-con- 
version superheterodyne receiver for AM, nar- receiver.-D. M. Eisenberg, Build This All-Band 
row-band FM, CW, and SSB operation. Supply VHF Receiver, 73 Magazine, Jan. 1975, p 105- 
is 13.6 V regulated. Article gives all circuits of 112. 



CHAPTER 21 

Counter Circuits 



Includes circuits for counting events and pulses over various ranges from to 
1.2 GHz singly, by 4s, or by decades, along with counting-rate meter, up/ 
down, multifunction, anticoincidence, PROM-controlled, free-running 
classroom-demonstration, and switch-closure counters driving multiplexed or 
continuous digital displays. See also Frequency Counter chapter. 




(1) MC14001 
(1) MC14583 
(3) MC14622 
(1) MC14534 
(1) MC75492 
(1) MC14511 
(1) STATEK Crystal, 

10 kHz, SX1H10K 



SW4 
SWS-7 



(1) DPOT Toggle Switch 
(II SPST Pushbutton Switch 
(11 SPDT Latching Push- 
button Switch 
(1) SPST Toggle Switch 
(3) BCD Thumbwheel Switches 
(1) MRD3055 
(1) 5.1 Mil. V.W 



R2-16.25.26 (17) 10kfi,!4 W 

R17 <1)470fi,KW 

R 18-24 (71 390 SI, '/. W 

R27 d) 1 Mil, '/• W 

R28, 31,33 (3)10kn,y.W 
R29, 30,35,36 (4) 470 kSi. ''• W 

R32.34 (21 560 S2, V. W 

1 Display, HP5082-7432 
1 Display, HP5082-7433 
P.C. Board, DCE Circuits 



5-DIGIT PRESET COUNTER— Basis of circuit is 
Motorola CMOS real-time MC14534 five-decade 
counter containing five ripple-type decade 
counters whose outputs are time-multiplexed 
by internal scanner. Time-base oscillator pro- 
vides 10-kHz crystal reference for clocking 
counters. Total current drain of system is 65 mA 



from S-V supply. When used to control quantity 
of Kerns placed in carton, each item interrupts 
light beam of photoelectric system to give 
count. External trigger output is connected to 
control mechanism that advances conveyor 
belt when box is full. Quantity of items desired 
per box is dialed on thumbwheel switches. Dis- 



play is used to indicate number of boxes filled. 
Other applications include count and display of 
number of interruptions of light beam, mea- 
surement of conveyor speed, and measurement 
of log lengths in sawmill.— A. Mouton, "Five 
Digit Accumulator/Elapsed Time Indicator," 
Motorola, Phoenix, AZ, 1975, AIM-743, p 3. 



234 



COUNTER CIRCUITS 



235 



BINARY OUTPUT* 



JUL? 



COUNT 




* ARRANGE BINARY OUTPUT 

LEDS IN THIS SEQUENCE: DCBA 



FOUR-LED BCD DISPLAY— Square-wave input 
pulses are counted by 7490 IC that drives LEDs 
indicating count in binary format up to 10 and 
then recycling. Can be used for classroom dem- 
onstrations of counters, flip-flop action, and bi- 
nary counting. Pulses can be obtained from UJT 
clock circuit operating at audio rate.— F. M. 
Mims, "Computer Circuits for Experimenters," 
Radio Shack, Fort Worth, TX, 1974, p 85-93. 



6 VOLTS 



1.2-GHz DECADE COUNTER— Motorola 
MCI 696 BCD-output counter provides direct 
counting of events at up to 1.2 GHz without 
prescaling. Connection shown is for AC cou- 
pling of input signals. Decoupling capacitors are 
used on power supplies and all unused pins. 
MC1696 provides division by 10, with output 
driving cascaded MC10138 biquinary counters 
and associated latches connected to drive five- 
decade display as covered in report.— J. Roy, 
"Event Counter and Storage Latches for High- 
Frequency, High-Resolution Counters," Moto- 
rola, Phoenix, AZ, 1975, EB-47. 




^To Clock of 
Next Stage 



14 15 

J_.01 f-F 

T-""TN /-rxChip 
, | Ca P s 




SELF-STARTING COUNTER— Addition of three 
logic elements eliminates need for separate 
starting switch when using National MM5736 
calculator chip as counter driving LED display. 
When reset switch is returned to normal posi- 
tion after pushing it to clear calculator, addi- 
tional parts serve to generate delayed pulse 
that gates digit output 2 into calculator and thus 
enters a 1 . This action resets counter with single 
manual operation.— M. Watts, "Calculator Chip 
Makes a Counter," National Semiconductor, 
Santa Clara, CA, 1974, AN-112, p 4. 



236 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



BCD DOWN COUNT OUTPUT 




CASCADED DOWN COUNTER— 4522 decimal 
divide-by-N counter is used with BCD thumb- 
wheel switch for each decade. Output is in BCD 
format, going down from preset number in 
range of 0-99. Decoded output of tens stage 
is connected to CF or carry-forward input of 
units stage. Only when both counters are in 
state is output provided. Preset number is 
then reloaded into counters. — D. Lancaster, 
"CMOS Cookbook," Howard W. Sams, Indian- 
apolis, IN, 1977, p 311-312. 



UP/DOWN COUNTER— Cascading of 4192 de- 
cade upfdown counters and use of two clocks 
give fully synchronous system for adding or 
subtracting count. Both clocks are normally 
held high. Low on up clock advances count. Low 
on down dock subtracts 1 from count. Clocking 
takes place on trailing or positive edge of neg- 
ative pulse. Parallel loading inputs are used to 
preset counter to any desired number. — D. Lan- 
caster, "CMOS Cookbook," Howard W. Sams, 
Indianapolis, IN, 1977, p 309-310. 



WEIGHTED 8CD OUTPUTS 



U CLOCK 



10 20 40 80 




10 20 40 80 



100 ZOO 400 800 



PARALLEL LOAD INPUTS 



A 



RS7490 



12,1 
9 



3. 6. 7, 10 



RS74W 



12. 1 



3, 6, 7. 10 



TO NEXT STAGE 
(PIN 14. RS7490I 






-vw- 



u 

II 



© 



±«y 



ALL RESISTORS ARE 
330 n 



MULTIDIGIT DEMONSTRATION COUNTER— 
Simple interconnection of RS7490 decade 
counter, RS7447 decoder, and 7-segment digital 
display for each desired digit makes ideal 



counter for classroom demonstrations and Sci- 
ence Fair exhibits. With two additional stages 
added, display reaches 9999 before recycling. 
Use 1N914 diode in series with battery to pro- 



tect against polarity reversal and reduce supply 
to 5 V for ICs.— F. M. Mims, "Integrated Circuit 
Projects, Vol. 6," Radio Shack, Fort Worth, TX, 
1977, p 53-63. 



COUNTER CIRCUITS 



237 



+5V 




II 



► 430 






► 430 



+5V 



Y . Y 7 *. Y 5 Y 4 Y 3 Y 2 Y, 
PROM 174186) 

ME F E D C B A 




I 



6 b 




I 



CLEAR (N) 



+5V 



6 e 



6 o 



PROM-CONTROLLED COUNTER— Universal 
counter can be set to count in any desired se- 
quence ranging from simple binary to pseu- 
dorandom, using only one programmable 
read-only memory chip and one 74174 edge- 
triggered flip-flop register chip. Version shown 
is 6-bit 64-state counter for which PROM is 



CLOCK IP) 



organized in 648-bit words. Pull-up resistors are 
required. Article covers application details, in- 
cluding expansion techniques. PROM outputs 
serve as data input to register chip, and register 
outputs provide PROM address inputs. — T. M. 
Farr, Jr., Read-Only Memory Controls Universal 
Counter, EDN Magazine. May 5, 1976, p 114. 



Y 



K 

CLEAR 

—0— 



'> SN7A0ON 
4 SN7473N 1 ~ | 



CLEAR 







Y 



M SN7400M 
•j SN7473N | — c 1 



FF3 
J Q 

K 
CLEAR 








!§l 


O 




"tirCT 






6 



Y 

ANTICOINCIDENCE— Developed for use with 
bidirectional counter circuits to avoid counting 
errors when up and down pulses occur simul- 
taneously. Operation is based on knowing max- 
imum frequency of separate data pulses. Out- 
puts 1 and 2 will be separated by at least one 
clock period even if inputs D1 and D2 occur si- 
multaneously. Article gives operating details. — 
J. H. Burkhardt, Jr., Anti-Coincidence Circuit 
Prevents Loss of Data, EDNIEEE Magazine, Jan. 
1, 1972, p 73. 



DECODED OUTPUTS 




10-POINT STEPPER— 4017 divide-by-10 counter 
routes input clock signal sequentially to each of 
ten output lines, with only selected output 
going high, internal circuit of IC is self-clearing 
walking ring that is glitch-free, with minimum 
overlap between outputs. Counters can be cas- 
caded to provide more steps. — D. Lancaster, 
"CMOS Cookbook," Howard W. Sams, Indian- 
apolis, IN, 1977, p 309. 



238 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CALCULATOR AS COUNTER— National 
MM5736 calculator chip is used with two 
DM75491 segment drivers and DM75492 digit 
driver for LED 6-digit display. Switches provide 
manual control of counter. To reset, push S, to 
clear calculator, push S 2 to enter a 1 , then push 
S 3 when new count is to be started. Current 
drive to LEDs is supplied by V cc through cur- 
rent-limiting resistors, giving power saving be- 
cause V C c can be less than V ss . Will drive large 
LED display.— M. Watts, "Calculator Chip 
Makes a Counter," National Semiconductor, 
Santa Clara, CA, 1974, AN- 112, p 4. 



1-MHz ^ ■ 

Reference /"" T" 
(CMOS Levels) 



1-MHz n. 

Reference S~ 

(MECL Levels) 



CMOS 
Reset 



MECL 

Reset GATE* 



1-SecTiming Chain 



^ 



MC14522 
Clk BCD Down 
Counter 



BCD Thumbwheel 
1-9-Second 
Sample Rate 




1 



DP1 DP2 DP3 DP4 

lk MC14522 C 

BCD Down 

Counter 



+5 
Vdc 



Supply 
Voltages 
CMOS +5 Vdc 
MECL -5.2 Vdc 



— T~ 

Sample 

Rate 

Counter 



MR SC 

MC14534 

Clk A 5-Decade CO 

Counter 




JT 



1/2 MC14013 



7^a 

MKCKIO * 



^ 



MC14022 

8-Stage 

Johnson Counter 

QO Q1 Q2 Q3 Q4 05 Q6 07 



yUHv , h 



QO Q1 Q2 03 Q4 Q5 



100 k 

r AArV "T" 



1/2 MC14013 




Reset FF 
'.001 nF 



220 - 

pF - 



1 kHz 



V 



TIME BASE FOR 1.2-GHz COUNTER— Provides 
1-s gate, latch strobing signals, 1-kHz signal for 
multiplexing displays, and digital sample rate 
control for high-frequency high-resolution 
counters. Timing chain divides 1-MHz external 



reference signal by 10 6 to give 1-Hz output. 
MC14534 five-decade counter generates 1-kHz 
multiplexing frequency with 20% duty cycle for 
blanking. Digital sample rate control is pro- 
grammed on BCD thumbwheel switch in incre- 



1 kHz 



ments ranging from 1 to 9 s, using single 
MC14522 BCD down counter. — J. Roy, "A Time 
Base and Control Logic Subsystem for High-Fre- 
quency, High-Resolution Counters," Motorola, 
Phoenix, AZ, 1975, EB-48. 



COUNTER CIRCUITS 



239 



<B» — L <3 

-Q™)o-^WV-i— 



©° — I 



Urt 



71 



/ 

/ "BESET" 



r»V O- 



/ s„ 



-^ ^ 



-^- 



V n S) SfScSdSc Sb St 



D1 D2 03 D40S DB V Dt 



_^L 



-^i- 




X 



DM7MB2 
DIGIT 
DRIVER 



CALCULATOR/COUNTER— Normal arithmetic 
functions of National MM5736 calculator chip 
are preserved while providing counting capa- 
bility, through use of MOS transistors Q1-Q4. 
When reset switch is pushed, pin D1 is con- 
nected to pin K 3 of calculator and calculator is 
cleared. C1 and C2 are discharged while S, is 
closed but are charged when it is released, gen- 
erating negative-going delayed pulse that 
causes a 1 to be entered into calculator. Delay 
allows clear function to be debounced by cal- 
culator chip. When S 2 is in count mode, Q4 is 
turned on and D6 is tied to D4, for doubling max- 
imum counting rate. Input pulse will now turn 
Q1 on, making calculator perform addition. Ad- 
ditional pulse adds 1 to sum. When S 2 is re- 
turned to calculate position, keyboard logic is 
returned to normal state. MM74C00 NAND 
gates can be replaced with MM74C02 NOR 
gates, and MOS transistors can be replaced 
with MM5616 CMOS switch.— M. Watts, "Cal- 
culator Chip Makes a Counter," National Semi- 
conductor, Santa Clara, CA, 1974, AN-112, p 6. 




DISPLAY: STANDARD 
DIP PIN SPACING 



"(5— If Q 1 P| N DIAGRAM ! B2 " 
KjiJ? (BOTTOM) ^Too) 

E 

QFlpnRn/iRi^/>niiiurci> nrr . ^ „ , room demonstrations and Science Fair exhibits. 

rfH^n, ^ c OUNTER-UJT relaxation os- Counter feeds corresponding BCD outputs to 6-V battery with 1N914 diode in series can be 

^ST" PU ' 8 ? *° ' nPUt "'" "" inpUt P ' nS " RS7447 decoder ,or conver - US8d in P |ac8 °* 5-V supply.-F. M. Mims. "In" 
14 of RS7490 decade counter at frequency de- sion into 7-segment decimal format for driving teg rated Circuit Projects, Vol. 2." Radio Shack 
termmed by setting of R2 and value used ford. Radio Shack 276-052 LED display. Ideal for class- Fort Worth, TX, 1977. 2nd Ed., p 41-56. 



240 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




TWO-CHIP COUNTER— Combination of Na- 
tional MM5736 calculator chip and DM75492 
digit driver for 6-digit LED display is suitable for 
applications where typical maximum counting 
rate can be about 100 Hz. Counter is reset man- 
ually by closing S, to clear calculator and closing 
S 2 to enter a 1. Operator now controls start of 
new count by pressing S 3 , without need for gat- 
ing count input.— M. Watts, "Calculator Chip 
Makes a Counter," National Semiconductor, 
Santa Clara, CA, 1974, AN-112, p 2. 



2-BIT BINARY— Sections of RS7473 dual flip- 
flop are connected to form simple counter that 
counts to three in binary with LEDs. By adding 
more flip-flop stages, count can be extended to 
higher values. If OFF LED represents and ON 
LED is 1, combinations 00, 01, 10, and 11 rep- 
resent 0, 1, 2, and 3, respectively. Input is re- 
stricted to low audio frequency so LED changes 
can be readily observed during demonstra- 
tions. — F. M. Mims, "Integrated Circuit Proj- 
ects, Vol. 6," Radio Shack, Fort Worth, TX, 1 977, 
p 23-32. 



1N914 



(t> 



R3 
270O 



®: © 



^ 



rEn rm rm mh m m m 




+ -•— 




CALCULATOR COUNTS UP TO 300 Hz— Logic 
elements used with MM5736 calculator chip 
provide self-starting counting action in range 
from 80 to 300 Hz. Increase in counting rate is 
obtained by feeding digit output 6 back to digit 
output 4, to bypass some internal logic of cal- 
culator.— M. Watts, "Calculator Chip Makes a 
Counter," National Semiconductor, Santa 
Clara, CA, 1974, AN-112, p 4. 



COUNTER CIRCUITS 



241 





Vss Vcc 








4 


Vss Vcc 

OM8995 
CE 
V DD 


3 








6 








5 


11 






9 




9 


■ a > 








12 




in ii 

8 9 


~1 

3 
















4 


V DD CE 

DM8895 

Vss V cc 






11 




5 


6 




COUNT ^ 


13 




12 


11 








7 




14 








8 


13 






6 




11 |16 








, 3 


„Sa Sb Sc Sd Se Sf Sg 

K MM5735 
2 CALCULATOR CHIP 

K Vdo 
1 D1 D2 03 D4 D5 D6 


I v cc 

-i-Vss 

10 

18 






5 

"Vo ^~* 


Sg Sf Se Sd Sc St Sa 

NSN66A 

LEO DISPLAY 


1 


1 






2 


1 


1 


1 


15 


14 




"" 










14 


DM75492 
DIGIT 
DRIVER 










12 


13 






10 


9 










5 


6 








3 


2 








8 


7 































LARGE LED DISPLAY— National MM5736 cal- 
culator chip is used with DM8895 segment 
driver that can be mask-programmed to source 
several values of current in range from 5 to 17 
mA per segment of LED display, permitting use 
of fairly large display. Display current comes 
from V cc supply terminal of DM8895 rather than 
from calculator chip. Combination serves as 6- 
decade counter driving 6-digit display. — M. 
Watts, "Calculator Chip Makes a Counter," Na- 
tional Semiconductor, Santa Clara, CA, 1974, 
AN-112, p3. 



XI 



RESET 
CLOCK-f-C|t 7490 UNITS 

A OUT B IN BCD 



zcr 



RESET 
(— 0( «_ 7490 TENS 

A OUT B IN BC D 



CLEAN RESET— Adding latch consisting of two 
7400 NAND gates to reset circuit of divide-by-77 
counter guarantees good reset. Reset pulse will 
always be half a clock period wide. — E. E. Hriv- 
nak. House Cleaning the Logical Way, 73 Mag- 
azine, Aug. 1974, p 85-90. 




6.5 - 9.5V 

: 4 e 



• — *— C2 
330k— T — ainF 



:^rE±^5~ 




CALCULATOR COUNTS BY 4s— Connection 
shown for National MM5736 calculator chip 
counts either up or down by 4s, as might be re- 
quired for keeping track of inventory in bin 
when parts are packaged in groups of 4. To 
count by numbers other than 1, desired number 
is entered into calculator during manual start 
operation. When S 2 is pushed, counter adds 4 to 
accumulated total. When S 3 is pushed, counter 
subtracts 4 from accumulated total. Logic ele- 
ments provide self-starting action of counter. — 
M. Watts, "Calculator Chip Makes a Counter," 
National Semiconductor, Santa Clara, CA, 1974, 
AN-112, p 5. 



242 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




DIGITAL COUNTING DEMONSTRATOR— 555 coder that drives 7-segment digital display. R1 peat, for classroom demonstrations.— F. M. 
timer serves as clock for driving RS7490 decade is adjusted to give clock frequency that makes Mims, "Integrated Circuit Projects, Vol. 6," 
counter feeding RS7447 BCD to 7-segment de- display cycle slowly through digits 0-9 and re- Radio Shack, Fort Worth, TX, 1977, p 53-63. 




FREOUENCY 

pr. riou 

FRfcOUi NCY HATIO 

TIME INTERVAL fTpO 
UNIT COUNTER 
OSCILLATOH FHEQ ♦" 



V+ 
C 



ICM 



7216B 21 
20 
19 



V- 
O 






101 



10-MH/ 
CRYSTAL 



T 



o 



DISPLAY OISPLAY 
BLANK TEST 



EXT 

OSC 

ENABLE 



lOpfj/, 

TVP 7] [control] '->/ 

[SWITCHES 



1L 



, 1 

D, 0(1 



=r. 



10k 




o n 


SEC 

01 


CYCLtS ( 
1 


t>, 


01 


10 [ 


L), 


1 


ino n 


Dj 


10 


1000 o 1 



EXT 
-OOSC 
INPUT 



LED 

OVERFLOW 

INDICATOR 



FREQUENCY/PERIOD/EVENT/TIME — Universal 
counter with 10-MHz maximum frequency pro- 
vides multiple functions with minimum number 
of components. Range of time period measure- 
ments is 0.5 /is to 10 s. Includes 10-MHz crystal 



oscillator, multiplex timing with interdigit and 
leading-zero blanking, as well as overflow in- 
dication. Decimal position is selectable. Eight- 
digit multiplexed LED display outputs of IC can 
switch up to 250 mA per digit for handling large 



displays. Maximum supply voltage is 6 V. — Low 
Cost Universal Counter Performs Wide Range of 
Functions, Computer Design, Aug. 1978, p 168 
and 170. 



COUNTER CIRCUITS 



243 



+6«. to +tSv. ■ 



FREE-RUNNING COUNTER DISPLAY— Atten- 
tion-getting circuit simply counts at predeter- 
mined rate while driving 3-digrt display using 7- 
segment LEDs. Circuit uses two sections of 401 1 
CMOS quad NAND gate to generate pulses at 
rate controlled by 100-megohm pot. Pulses trig- 
ger 4026 counters connected as shown, with 
outputs a-g of each going to 7-segment LED dis- 
play. When all three displays reach 9, next pulse 
resets all to and count continues. Auxiliary cir- 
cuit at upper right uses remaining sections of 
4011 as flip-flop controlled by touch-plate 
switches; bridging gap between center and 
grounded plates with finger makes counter run. 
Bridging other gap resets counter to and holds 
it there. If reset is not used, connect input pins 
8, 9, 12, and 13 of unused gates to pin 14.— J. A. 
Sandler, 9 Easy to Build Projects under $9, Mod- 
ern Electronics, July 1978, p 53-56. 




NOTES: 



+6v. to +15v to Pin 14 of 4011 return to Pin 7 of 4011 

No dropping resistors needed for most .3 to .8 inch LED displays. 




COUNTING-RATE METER— Uses three Optical 
Electronics 9827 opamps to amplify, square up, 
and integrate input pulses from event detector, 
to give integrated DC voltage that is function of 
counting rate. This voltage is compressed by 
2538 DC logamp having 60-dB dynamic range 



for driving chart recorder. Values of R and C de- 
pend on counting rate. Well-regulated power 
supply is required because this determines am- 
plitude of squared pulses that drive integrator. 
Applications include counting photons of pho- 
tomultiplier or nuclear particles of solid-state 



detector. Logamp compresses output of inte- 
grator to eliminate need for scale changing 
while giving constant accuracy over wide dy- 
namic range of counting rates. — "Logarithmic 
Counting Rate Readout," Optical Electronics, 
Tucson, AZ, Application Tip 10106. 



CHAPTER 22 

Current Control Circuits 



Includes fixed, adjustable, and voltage-controlled current sources, bilateral 
sources, current limiters, current regulators, current sink, current-controlled 
oscillator, power supply monitor, and electronic fuse. 



5 inA WITH VARIABLE-SLOPE START-UP— 
Low-cost NSL5022 LED typically has 1 .6-V drop 
at 2 mA, to produce constant 0.9 V across 390- 
ohm emitter resistors in circuit shown. Use of 
two current sources, each feeding other's LED 
reference, eliminates all voltage defects except 
for small voltage-dependent changes in transis- 
tor parameters. Adding 240K slope resistor can- 
cels these changes, holding current constant 
within 0.1% over supply voltage range of 5-20 
V. Applications include use as voltage divider 
with gain, Q multiplier for tuned circuits, and 
bias compensation. — P. Lefferts, Variable Slope 
Current Source Starts at 2.5 V, EON Magazine, 
Nov. 5, 1975, p 100. 





POT CONTROL — Circuit makes current through 
linear pot a linear function of rotational angle of 
pot. Article gives design equations. Current i, 
through R, is used to charge C, which is period- 
ically discharged by UJT when trigger voltage 
is reached. Frequency of output sawtooth is 
proportional to i, and hence to angle of rotation 
of pots. To set up, adjust pots to give maximum 
sawtooth frequency and adjust preset R 5 for re- 
quired maximum frequency. Set pols to other 
extreme and reset R 3 for required minimum fre- 
quency. — A. Armit, Linear Current/Rotation 
Control, Wireless World, Dec. 1975, p 576. 



244 



CURRENT CONTROL CIRCUITS 



245 




V (N >OV 



PRECISION CURRENT SINK— R1 serves as cur- 
rent-sensing resistor providing negative feed- 
back for opamp to enhance true current-sink 
nature of circuit. Both JFET and bipolar have in- 



herently high output impedance as required for 
high-accuracy current sink. — "FET Databook," 
National Semiconductor, Santa Clara, CA, 1977, 
p 6-26-6-36. 



28V 

ACO— 

INPUT 



-w- 



-WA- 

10k 



10k 

-vw- 



— ww — QryJ. (?2 — ww 



1N914 



-vw- 

10k 



6,,Q 2 =U290 



28-VAC CURRENT LIMITER— DualJFETs in Volt- 
age-sharing arrangement protect output of 28- 
VAC power amplifier. Transistors should be 
matched for l DSS . During positive half-cycle of 
input, Q 2 operates as current limiter and Q, as 
source follower. If Q, does not supply enough 
current, drain voltage of Q 2 drops and makes Q, 



turn on further. Conversely, if Q, supplies too 
much current, Q 2 drain voltage rises and tends 
to turn Q, off. On negative half-cycle, Q, be- 
comes limiter and Qj is source follower. J. P. 

Thompson, Current Limiter Protects Amplifier 
from Load Faults, EDN Magazine, June 5, 1978, 
p 148 and 150. 



« 



-L 



LOAD 



JFET CURRENT SINK— Simple circuit effec- 
tively raises load operating point of current-sen- 
sitive device by shunting current through JFET 
having nonlinear action. JFET type is not criti- 
cal. Applications include improvement of thy- 
ristor noise performance by diverting current 
around load.— V. Gregory, FET Current Sinks 
Raise Operating Points, EDN Magazine, Feb. 20, 
1974, p 81. 




20-mA FLOATING SOURCE— Battery-operated 
circuit shown gives adequate stability for 
strain-gage bridge. Uses four alkaline penlight 
cells to provide ±3 V for 741 opamp. E, is chosen 
to give adequate voltage for intended load at 
maximum load current. Temperature stability 
is 0.7 /iA/°C from to 50°C— R. Tenny, Isolated 
Current Source, EDN Magazine, April 20, 1973, 
p85. 



t H N H H y 




4-20 mA SOURCE— Digital input to multiplying 
digital-to-analog converter determines load 
current in range of 4 to 20 mA with 1 5.6-juA res- 
olution. R, adjusts ratio of full-scale to zero- 
scale current at output 1 of MDAC, and R 3 sets 



circuit offset and span to give correct end-range 
currents for load. Maximum load compliance is 
25 V. Opamp types are not critical. — J. Wilson 
and J. Whitmore, MDAC's Open Up a New 
World of Digital-Control Applications, EDN 
Magazine, Sept. 20, 1978, p 97-105. 




HIGH-COMPLIANCE CURRENT SOURCE— Non- 
inverting input of LM143 high-voltage opamp 
senses current through R4 to establish output 
current that is proportional to input voltage. 
With ±38 V supply, compliance of current 
source is ±28 V.— "Linear Applications, Vol. 2," 
National Semiconductor, Santa Clara, CA, 1976. 
AN-127,p3. 



246 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




PRECISION CURRENT SOURCE— 2N5457 JFET 
and PN2222 bipolar transistor serve as isolators 
between output and current-sensing resistor 
R1. LM101 opamp provides high loop gain to 



assure that circuit acts as current source.— 
"FET Databook," National Semiconductor, 
Santa Clara, CA, 1977, p 6-26-6-36. 



MONITOR 
OUTPUT 

Rt R3 
VOUT--=-H 




POWER SUPPLY MONITOR— R1 senses output 
current of power supply. PN3684 JFET is used 
as buffer because source and drain currents are 
equal, so monitor output voltage accurately re- 
flects current flow of power supply. — "FET Da- 
tabook," National Semiconductor, Santa Clara, 
CA, 1977, p 6-26-6-36. 



R S « R 3 




ER 4 IFRl»R3ANDR 2 "R4+fl5THEN 

rZrZ I I IS INDEPENDENT OF VARIATIONS 

IN R L . 



BILATERAL CURRENT SOURCE— Output cur- 
rent through load is constant within 2% of value 
related to input voltage and resistor values, re- 
gardless of variations in load from 10 to 2000 



ohms. Circuit is built around Precision Mono- 
lithics OP-08 opamp.— "Precision Low Input 
Current Op Amp," Precision Monolithics, Santa 
Clara, CA, 1978, OP-08, p 7. 



7.I5 



.02 
DISC 



M A723 
I4PIN DIP 



^.OOI 
DISC 



I5K 



GROUND 

0.5 mA FOR 0-50 KILOHMS— Current source 
uses Fairchild pA723 voltage regulator operat- 
ing from ordinary unregulated supply not over 
40 VDC. Regulator has built-in 7.15-V reference. 



Output current is well within 1% of 0.5 mA for 
load impedances from 0-50K.— L. Nickel, Con- 
stant Current Sources, 73 Magazine. March 
1974, p 29. 




CURRENT REGULATOR— Combines zener with 
opamp in bootstrap configuration. Regulated 
output current I, can be any value less than I, 
but must be much greater than opamp bias cur- 
rent. Current in zener is set by R1 to provide 
minimum of 1 mA. Performance can be im- 
proved by using Motorola MC1403 or other 2.5- 
V three-terminal voltage reference in place of 
zener.— W. Jung, An IC Op Amp Update, Ham 
Radio, March 1978, p 62-69. 



1u.A" 



input 



' '2mA 



- + 14V 



^ 




output 



-0V 



CURRENT SOURCE AS TRANSISTOR LOAD— 
Reverse-biased germanium diode serves as 
voltage-independent current source for loading 
silicon transistors in linear amplifier having 
voltage gain of 50 and -3 dB bandwidth of 16- 
4000 Hz. In addition to low cost, circuit design 
permits reliable operation of reliable micro- 
power circuits over wide temperature range at 
optimum current drain. — M. G. Baker, Low-Cur- 
rent Source, Wireless World, April 1976, p 61. 



CURRENT CONTROL CIRCUITS 



247 



6mH,3A -hivOC 



PULSATING 
DC INPUT 



6OO11F-J- 
30 V 



270.2W 



20 V 



100 k 



0, 
2N930 



2N2905A 



0' 
2N2226 






<? 




2N22I9 



3-A LIMITER — Simple current limiter protects 
itself from overdissipation during shorted out- 
put, while handling capacitor or cold-filament 
loads that momentarily act like shorts. R3 is ad- 
justed so starting current is high enough to 
begin heating cold filament. As filament voltage 



0.2 
5W 



;"(.< 



increases to about 100 mV, Q4 and Q 3 tum off, 
allowing load current to rise to 3-A limiting 
value.— L. G. Wright, Short-Protected Current 
Limiter Ignores Inrush Currents, EEE Magazine, 
Sept. 1970, p 89-90. 



+15 V 



4.7k 
IN»— j] WV 




CONSTANT-CURRENT LED— National NSL4944 
LED having built-in current control features can 
be used in simple circuit shown to provide cur- 
rent limiting and short-circuit protection for 15- 
V supply. Even with output shorted, LED draws 
only a little more than rated current. — "Linear 
Applications, Vol. 2," National Semiconductor, 
Santa Clara, CA, 1976, AN-153, p 3. 




TO dc POWER 
SUPPLY 



ELECTRONIC FUSE— Combination of SCR and 
line relay gives faster action than circuit breaker 
for protection against current overload. Closing 
S, momentarily energizes relay, completing 
current path from supply to load. Overload cur- 
rent increases voltage drop across R, to above 
0.65 V, switching on SCR and thereby shorting 



TO LOAD 



R, ~0.65/I MAX 

relay coil to make it open. S, must be pressed 
again to reset relay. For adjustable dropout, 
gate of SCR can be connected to pot placed 
across R,.— R. Quong, Resettable Electronic 
Fuse Consists of SCR and Relay, Electronics, 
Sept. 15, 1977, p 117. 



+V CC (+15V) 



20k. 1% 
I — vW- 




L0AD 



I 



J- 



20k, 1% 



VOLTAGE CONTROL— Improved voltage-con- 
trolled current source uses complementary 
transistors in opamp feedback loop. Common- 
mode voltage at input to opamp is always near 
zero. Circuit was designed for use in integrator 
having ground-referenced integrating capaci- 
tor, to produce 1 mA/V. R 3a and R 30 sense current 
through Q, and Qj, so voltage proportional to 



-V cc (-15V) 

difference is fed back to input of opamp forcom- 
parison with input voltage. Zener voltages de- 
termine quiescent-current level. Frequency re- 
sponse is limited to 1 MHz by performance of 
specified opamp. — P. T. Skelly, Voltage-Con- 
trolled Current Source, EDNIEEE Magazine, 
Aug. 1,1971, p 45-46. 




(8>» OUTPUtJ - ]! - ] 



CURRENT-CONTROLLED OSCILLATOR— 

Makes use of proportional relationship be- 
tween input current li and amplifier input bias 
current l AE >c of CA3094 programmable opamp. 
Linearity is within 1% over middle half of char- 
acteristic. Circuit can be used for voltage input 
if voltage is applied to pin 5 through appropriate 
dropping resistor R. Output is square wave. — 
"Circuit Ideas for RCA Linear ICs," RCA Solid 
State Division, Somerville, NJ, 1977, p 4. 




50 pF- 



100-mA CURRENT REGULATOR— Two-termi- 
nal circuit using LM195 power transistor has 
low temperature coefficient and operates down 
to 3 V. 2N2222 controls voltage across current- 
sensing resistor R2 and diode D1. Voltage 
across sense network is base-emitter voltage of 
2N2222 plus 1.2 V from LM113. R1 sets current 
through LM113 to 0.6 mA.— R. Dobkin, "Fast IC 
Power Transistor with Thermal Protection," Na- 
tional Semiconductor, Santa Clara, CA, 1974, 
AN-110, p6. 



CHAPTER 23 

Data Transmission Circuits 



Includes line driver, line receiver, modem, bit-rate generator, coder-decoder, 
FSK demodulator, signal conditioner, optoisolator, PDM telemetry, active 
bandpass filter, and other circuits used for transmitting digital data and digital 
speech over twisted-pair, coaxial, or balanced line. 



£ 1 » 

1 MHz ,-L, 



Crystal 



Transmit Data - 



Transmit Break - 



Data Terminal, 



Break Release- 



Receive Break- 
Clear-to Send- 
Receive Data- 



Enable Lon g Space 
Disconnect 



Enable Spa ce 
Disconnect 



All other pins open. 



V D D v ss 



T 




To CBT Data Coupler 



ANSWER MODEM— Transmits on upper chan- modem interface to transmission network, tor, demodulator, and supervisory control func- 

nel (mark 2225 Hz and space 2025 Hz) and re- Bandpass filter allows only desired receive sig- tions.— G. Nash, "Low-Speed Modem Funda- 

ceives on lower channel (mark 1270 Hz and nals to be seen by limiter and demodulator. mentals," Motorola, Phoenix, AZ, 1974, AN-731, 

space 1070 Hz). Buffer and duplexer provide Motorola MC6860 modem IC contains modula- p 6. 



248 



DATA TRANSMISSION CIRCUITS 



249 



24.3 k 
O— VWV- f 



:0.01 >217.3 k 



L r^ 29. as 



< 1/2 MC14! 

199.8 < 



Z^O.01 $267.2 k 
29. 85 k 



0.01 
242.5 

i 1 



i- 






1/2 MC1458 
458.9 




fHHq>i- 

< 0,01 ^^ 

< 1/2MC14! 



i i 



All capacitors are in fj.F . 

BANDPASS ORIGINATE FILTER— Provides gain 
of over 15 dB between 1975 and 2275 Hz, to ac- 
cept 2025-2225 Hz signals of low-speed modem 
system using Motorola MC6860 IC. — J. M. 
DeLaune, "Low-Speed Modem System Design 
Using the MC6860," Motorola, Phoenix, AZ. 
1975,AN-747,p13. 



V = 3V PEAK 
l -60mA PEAK 
OVERSHOOT =17% 
Tj - 60m 




FAST-SETTLING COAX DRIVER— Suitable for 
use as radar pulse driver, video sync driver, or 
pulse-amplitude-modulation line driver. Uses 
Harris HA-2530/2535 wideband amplifier having 
high slew rate. Usable bandwidth is about 100 
kHz when connected for noninverting operation 
as shown. Driver output is 60 mA into 60-ohm 
load. 5% settling time is 60 ns. — "Linear & Data 
Acquisition Products," Harris Semiconductor, 
Melbourne, FL, Vol. 1, 1977, p 7-54 (Application 
Note 516). 



SYNCHRONOUS PDM 




SYNCHRONOUS SAWTOOTH FOR PDM TELE- 
METRY — Circuit generates highly linear ramp 
that is reset to zero by each clock pulse. When 
ramp exceeds analog value of unknown input 
voltage, pulse is terminated. R1, R2, and CI 
form integrating network around opamp. Vary- 
ing R2 changes slope of ramp output. — J. Sprin- 
ger, Build a Sawtooth Generator with Three ICs, 
EDN Magazine, Nov. 15, 1970, p 49. 



INTERFACES FOR 100-OHM LINE— Permits 
transferring data signals from SA900/901 dis- 
kette storage drive to location of MC6800 mi- 
croprocessor up to maximum of 20 feet away 
through 100-ohm coax. Data line drivers used 
are capable of sinking 100-mA in logic true state 
with maximum voltage of 0.3 V with respect to 
logic ground. When line driver is in logic false 
state, driver transistor is cut off and voltage at 
output of driver is at least 3 V with respect to 
logic ground. — "Microprocessor Applications 
Manual" (Motorola Series in Solid-State Elec- 
tronics), McGraw-Hill, New York, NY, 1975, p 5- 
211-5-212. 




250 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



TRANSMITTER 



(Transmitter) 




(Receiver) 



Data 



Output 



OPTICALLY COUPLED DATA LINK— 322 com- 
parator at transmitter end of link drives LED of 
MCD 2 optoisolator which accepts TTL input. 
Receiver is similar comparator having addi- 
tional biasing to match photodiode output of 
optoisolator. Complete system is noninverting, 
with delay of about 2 /us. Receiver can have any 
supply within 4.5-40 V range of 322. Transmit- 
ter should be matched to its supply voltage by 
selecting R 2 according to equation shown. — W. 
G. Jung, "IC Timer Cookbook," Howard W. 
Sams, Indianapolis, IN, 1977, p 156-158. 



RECEIVE FILTER— Used as prefilter having 
controlled group-delay distortion, ahead of re- 
ceiving modem in data transmission system. 
Values shown are for 950-1400 Hz answer filter. 
For 1 900-2350 Hz originate filter, change critical 
values to those given in parentheses. — D. Lan- 
caster, "TV Typewriter Cookbook," Howard W. 
Sams, Indianapolis, IN, 1976, p 180-182. 



INPUT 
(LOW - Z 
SOiRCEl 




4558 OR 741SOP AMPS 



950-1400 H; ■ NORMAL VALUES ■ ANSWER FILTER 
1WO-P350 HI ■ (PARENTHETICAL VALUES) ORIGINATE FILTER 






WITHOUT 
SCHOTTKY DIODES 


WITH 
SCHOTTKY DIODES 


SWITCH 
A 


SWITCH 
B 


UNITS 


t 


<1 


30 


90 


1 


30 


90 


- 




m 


•p 


100 


165 


340 


55 


75 


215 


OPEN 


OPEN 


nsec 


45 


125 


310 


45 


70 


185 


OPEN 


CLOSED 


nsec 


46 


60 


125 


45 


60 


125 


CLOSED 


CLOSED 


nsec 



E 



PROPAGATION TIMES SHOWN EXCLUDE DRIVER AND LINE DELAYS. 



Vcc- 



3- 



ST? 5 . 



HCPL-2St£ 



3 
3- 



3- 



-3- 
3 



SWK 



3- 



NAND 
FLIP- 
FLOP 



V 



V 



A? 



POLARITY-REVERSING SPLIT-PHASE DRIVE— 
Half of 9614 polarity-reversing line driver feeds 
pair of Hewlett-Packard HCPL-2602 optically 
coupled line receivers through coax cable. 
Cable-grounding switches A and B change per- 



formance. Closing only switch B enhances com- 
mon-mode rejection but reduces propagation 
delay slightly. Closing both switches optimizes 
data rate. Schottky diodes at receiver inputs im- 
prove data rate. NAND flip-flop at output 



greatly improves system noise rejection in split- 
phase termination of line. — "Optoelectronics 
Designer's Catalog 1977," Hewlett-Packard, 
Palo Alto, CA, 1977, p 158-159. 



DATA TRANSMISSION CIRCUITS 



251 



9 ush T 

:o Talk V^ 
<ev ^ 



Digital Input 



(Norm, 
open) 



Analog .£ 

Input ™ 



Digital Output 



Encode/ Decode 



.JF 



Analog 
Output 



600 

V TH 12 




V C C'2 
R«f 



Digital 
Out 



Clock 
16 kHi 



♦ 3.0 



16 V CC 



Shift Registei 



Slope Polarixy\_ 
Switch 



T 



3.3 k Rp 




Vs 



CVSD ENCODER FOR SECURE RADIO— Moto- 
rola MC3417 continuously variable slope delta 
modulator-demodulator IC is used as 16-kHz 
simplex voice coder-decoder for systems re- 
quiring digital communication of analog sig- 
nals. Clock rate used depends on bandwidth re- 
quired and can be 9.6 kHz or less for voice-only 
systems. Analog output uses single-pole inte- 
gration network formed with 0.1 /«F and 10K. 
Report covers circuit operation in detail for var- 
ious applications. — "Continuously Variable 
Slope Delta Modulator/Demodulator," Moto- 
rola, Phoenix, AZ, 1978, DS 9488. 



5-MHz COAX LINE DRIVER— Combination of 
Harris HA-2530 wideband inverting amplifier 
and HA-2630 unity-gain current amplifier pro- 
vides 20-dB gain with extremely high slew rate 
and full power bandwidth even under heavy 
output loading conditions. — "Linear & Data Ac- 
quisition Products," Harris Semiconductor, 
Melbourne, FL, Vol. 1, 1977, p 2-47-2-50. 



_TL 




"L_T 



NOTE: RI and R2 lead length should be minimal. 



o-*> 



ia> 



sv 
O 



CH 



560 



H 



i ® « 



£> 



I GND 

-I 






TWISTED 
PAIR 



-^ 



son< 




TTL COMPATIBLE 
OUTPUT 



BALANCED-LINE TRANSMISSION— Transmits 
data at rates up to 0.5 MHz over twisted pair to 
Texas Instruments SN75152 dual-line receiver. 
Other section of receiver is identical and can 



handle additional twisted-pair input. Diodes in 
lines are required only for negative common- 
mode protection at driver outputs. System has 
high common-mode voltage capability. 
SN75450 is dual peripheral driver for high-cur- 



rent switching at high speeds.— "The Linear 
and Interface Circuits Data Book for Design En- 
gineers," Texas Instruments, Dallas, TX, 1973, 
p 8-78. 



252 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



220 
-AV- 



220 

ChmM 



1 •W 1' 



— j^T)>^ 



4iH 

SN74H01 



"S=?-E> 



COAX DRIVER AND RECEIVER— Uses two TTL 
gates of SN74H01 package to form either driver 
or receiver for transmitting data over RG59 or 
RG174 coax at rates exceeding 10 megabits per 
second, with distance increasing from 400 me- 
ters at 10 Mb/s to over 1000 meters at 100 kb/s 
for RG59 and lesser distances for RG174. Can 
also be used for twisted-pair lines but at lower 
data rates. Bias gate G 3 exhibits low output 
impedance, for terminating channel load resis- 
tor R 6 . — R. W. Stewart, Two TTL Gates Drive 
Very Long Coax Lines, BDN Magazine, Oct. 1, 
1972, p 49. 



103-COMPATIBLE MODEM— Motorola 4412 IC 
converts serial data, usually to and from uni- 
versal asynchronous receiver-transmitter, into 
tones suitable for telephone communication. In 
originate mode, logic is transmitted as 1070 
Hz and logic 1 as 1270 Hz. In answer mode, logic 
is transmitted as 2025 Hz and logic 1 as 2225 
Hz. Modems are used in pairs, with receiver re- 
sponding to tone group not being transmitted. 
Speed capability is up to 300-baud data rate. 
Output is 300 mVRMS into 100K load.— D. Lan- 
caster, "CMOS Cookbook," Howard W. Sams, 
Indianapolis, IN, 1977, p 133. 




TRANSMIT TONE 
OUTPUT 




MODEM — Developed as part of TV terminal for frequencies of 1270 Hz for mark and 1070 Hz for connection to telephone lines, and use of 

microprocessor, to permit communication over space, with answer frequencies of 2225 Hz for modem. — R. Lange, Build the $35 Modem, Kil- 

telephone line with time-sharing computer sys- mark and 2025 Hz for space. AY-5-1012 UART obaud, Nov. 1977, p 94-96. 

tern. Uses Motorola MC14412 modem chip for serves as parallel interface to microprocessor, 

full-duplex FSK modulation having originate Article covers operation, construction, testing. 



DATA TRANSMISSION CIRCUITS 



253 



Voice/N on -Voice 
SELECT 



Clock 
I nput 
37.7 kHz 



Digital 
Output 

<> 37.7 Bits 



(V cc /2) 




£-■ 



200 k 
-VW-" 



TELEPHONE-QUALrTY CODER-DECODER— 
Uses Motorola MC3418 continuously variable 
slope delta modulator-demodulator IC to give 
over 50 dB of dynamic range for 1-kHz test at 
37.7K bit rate. At this rate, 40 voice channels can 
be multiplexed on standard 1 .544-megabit tele- 
phone carrier facility. IC includes active com- 
panding control and double integration for im- 
proved performance in encoding and decoding 
digital speech. Opamp types are not critical. — 
"Continuously Variable Slope Delta Modulator/ 
Demodulator," Motorola, Phoenix, AZ, 1978, DS 
9488. 



REZEROING AMPLIFIER— Used where input 
signal has unknown and variable DC offset, as 
in telemetry applications. Rezero command line 
is enabled while ground reference signal is ap- 
plied to input, making CI charge to level pro- 
portional to DC offset of system. When rezero 
line is deactivated, amplifier becomes conven- 
tional inverter, subtracting system offset and 
giving true ground-referenced output. For 10-V 
full-scale system requiring 0.1% (10-mV) accu- 
racy, amplifier needs rezeroing reference every 
100 ms.— "Linear Applications, Vol. 1," Na- 
tional Semiconductor, Santa Clara, CA, 1973, 
AN-63, p 1-12. 



INPUT O 



TTL 
RE ZERO COMMAND 




OUTPUT 



I 1/2AH0133 | 



0.01 tif POLYSTYRENE 



1/2 9614 



HEWLETT-PACKARD 
6082-2835 






WITHOUT 
SCHOTTKY DIODE 


WITH SCHOTTKY DIODE 


UNITS 




R -0 


R -0 


R - 33!! 


t 


<1 


30 


90 


<1 


30 


90 


<1 


30 


90 


tn 


tPHL 


210 


365 


450 


50 


80 


235 


50 


70 


200 


nsec 


tPLH 


35 


45 


60 


35 


45 


60 


35 


45 


60 


nsec 




.01 



_L v 

15pF 



/h 



PROPAGATION TIMES SHOWN EXCLUDE DRIVER AND LINE DELAYS. 



POLARITY-REVERSING DRIVE— Half of 9614 
polarity-reversing line driver feeds Hewlett- 
Packard HCPL-2602 optically coupled line re- 
ceiver through shielded, twisted-pair, or coax 



cable. Data rate is improved considerably by 
using Schottky diode at input of receiver. Best 
data rates are achieved when t PHL (propagation 
delay time to low output level) and t PLH (propa- 



gation delay time to high output level) are clos- 
est to being equal.— "Optoelectronics De- 
signer's Catalog 1977," Hewlett-Packard, Palo 
Alto, CA, 1977, p 158-159. 



254 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



► 12V 

o 



o.vf: 



+ 12VO- 



10KJ! 
I — v/v- 




XR 2211 



510KI) 




-O DATA OUTPUT 



-O Q LOCK DETECT OUTPUT 



:c F 



FSK DEMODULATOR WITH CARRIER DETECT— 
Exar XR-2211 FSK demodulator operating with 
PLL provides choice of outputs when carrier is 
present; pin 5 goes low and pin 6 goes high 
when carrier is detected. With pins 6 and 7 con- 
nected, output from these pins provides data 
when FSK is applied but is low when no carrier 
is present. Circuit performance is independent 
of input signal strength over range of 2 mV to 
3 VRMS. Center frequency is 1/C,R, Hz, with val- 
ues in farads and ohms. Choose frequency to fall 
midway between mark and space frequencies. 
Used in transmitting digital data over telecom- 
munication links. — "Phase-Locked Loop Data 
Book," Exar Integrated Systems, Sunnyvale, 
CA, 1978, p 57-61. 



-OQ LOCK DETECT OUTPUT 



FSK DETECTOR— Exar XR-S200 PLL IC is con- 
nected as modem suitable for Bell 103 or 202 
data sets operating at data transmission rates 
up to 1800 bauds. Input frequency shift corre- 
sponding to data bit reverses polarity of DC out- 
put voltage of multiplier. DC level is changed to 
binary output pulse by gain block connected as 
voltage comparator. — "Phase-Locked Loop 
Data Book," Exar Integrated Systems, Sunny- 
vale, CA, 1978, p 9-16. 




FSK INPUT 
SIGNAL 



DEMODULATED 
LOGIC OUTPUT 

■o — o 



C c = COUPLING CAPACITOR 
Cj'BVPASS CAPACITOR 






R 


= 0. C 


-0 


R = 


32!!, C-0 


R = 33S>, C = 430pF 


UNITS 


1 


<1 


30 


90 


<1 


30 


90 


<1 


30 


90 


m 


«PHL 


40 


50 


75 


40 


50 


100 


30 


45 


75 


nsec 


tPLH 


45 


65 


175 


40 


50 


80 


40 


45 


75 


nsec 



_L_ .01 

uF 



v o 



~7h 



PROPAGATION TIMES SHOWN EXCLUDE DRIVER AND LINE DELAYS. 



POLARITY-NONREVERSING DRIVE— Hewlett- 
Packard HCPL-2602 optically coupled line re- 
ceiver handles high data rates from shielded, 
twisted-pair, or coax cable fed by 74S140 line 
driver. Reflections due to active termination do 
not affect performance. Peaking capacitor C and 



series resistor R can be added to achieve high- 
est possible data rate. C should be as large as 
possible without preventing regulator in line re- 
ceiver from turning off during negative excur- 
sions of input signal. Highest data rates are 
achieved by equalizing t PHL (propagation delay 



time to low output level) and t PL H (propagation 
delay time to high output level). — "Optoelec- 
tronics Designer's Catalog 1977," Hewlett- 
Packard, Palo Alto, CA, 1977, p 158-159. 



DATA TRANSMISSION CIRCUITS 



255 




DIFFERENTIAL LINE DRIVER— Uses Motorola 
MC75110L line driver and MC75107L receiver 
with twisted-pair transmission line having at- 
tenuation of 1 .6 dB per 100 feet at 10 MHz. Clock 
rate is 18.5 MHz. With push-pull driver shown, 
single pulse corresponds to transmission of 1 
followed by series of Os; one line is then at 
ground and the other at -300 mV. Arrangement 
is suitable for party-line or bus applications. — 
T. Hopkins, "Line Driver and Receiver Consid- 
erations," Motorola, Phoenix, AZ, 1978, AN- 
708A,p11. 



Rl = R2 = R3 = R4= 5on 
II = 600 Ft of Twisted Pair Line 
No. 20 Wire With 0.6 Turns/Ft. 



+ 5 V 



' 2 k 



r 



"*"« > o i j y tx 




I MC75451P I 



1/4 MC7400P 



)0 Q ( Output 



< 100 



SINGLE-ENDED LINE DRIVER— Supplies 4.2-V point-to-point system. Requires only single +5 ceiver Considerations," Motorola, Phoenix AZ 
input pulse to twisted-pair transmission line for V supply.— T. Hopkins, "Line Driver and Re- 1978, AN-708A, p 14. 



CLOCK 
DATA 



A) SYMMETRICAL CLOCK 
J4 9014 



100pF 



D= 



CLOCK 



DATA 







8j 


7*9014 °l 




If" U 


J Q 
K 


r 




T 





B) DOUBLE FREQ. CLOCK 



EXCLUSIVE-OR GATES— Use of retriggerable 
mono with EXCLUSIVE-OR gates simplifies de- 
sign of both transmitter and receiver for han- 
dling binary phase-modulated digital data over 
single line. With 50% duty-cycle clock at trans- 
mitter, clock and data signals are applied to in- 



-J LINE | — e-P 



^D&j; 



55 



9014 



i. -— M 

I 9601 f—* -~* 



J -Q 
CP 

DATA 
K «- 



puts of 9014 to generate output signal for line. trigger 9601. System remains synchronized as 

At receiver, clock and data stream are regener- long as pulse width of mono is between 50% 

ated by 9601 adjusted to 75% of data-bit time and 100% of data-bit time.— P. Atfke, Exclusive- 

and connected in nonretriggerable mode. One OR Gates Simplify Modem Designs, EDN Mag- 

EXCLUSIVE-OR gate and an EXCLUSIVE-NOR azine, Sept. 15, 1972, p 43. 
gate connected as inverting delay element will 



256 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



SINEWAVE 
OUTPUT 

,9 * 



0/L 



SOUAREWAVE 
FSK OUT 




3-KILOBAUD FULL-DUPLEX FSK MOD EM— Val- 
ues shown are for 13-kHz bandwidth, 1070 Hz 
for mark and 1270 Hz for space, using Exar XR- 
2206 function generator and XR-2211 FSK de- 
modulator. Report gives design procedure. 
Supply can be +12 V. — "Phase-Locked Loop 
Data Book," Exar Integrated Systems, Sunny- 
vale, CA, 1978, p 57-61. 



DUAL-LINE RECEIVER FOR COAX— Single 
Texas Instruments SN751S2 IC contains two re- 
ceiver sections, each taking input from separate 
coax. Other receiver section (not shown) is iden- 
tical and provides similar TTL output for its 
coax. Driver shown has OR capability for feed- 
ing singje coax. Receiver has adjustable noise 
immunity and continuously adjustable hyster- 
esis control (not shown). — 'The Linear and In- 
terface Circuits Data Book for Design Engi- 
neers," Texas Instruments, Dallas, TX, 1973, p 
8-78. 



.__t_. 



mX 



• o-» 



qCX 



i - 
i 



+■ 

L_ SN7M51_ _J 



RG63B/U 
CABLE 




+5V 




BUS TRANSCEIVER— Designed for use in bus- 
organized data transmission systems intercon- 
nected by terminated 120-ohm lines. Up to 27 
driver/receiver pairs can be connected to com- 



mon bus. One two-input NOR gate is included 
in National DS8641 quad unified bus transceiver 
package to disable all drivers in package simul- 
taneously. — "Interface Integrated Circuits," 



National Semiconductor, Santa Clara, CA 1975, 
p 3-17-3-18. 



DATA TRANSMISSION CIRCUITS 



257 



+5V 



INPUT 




LINE DRIVER FOR LED— Single-ended input is 
converted to balanced differential drive for 
feeding 75-ohm transmission line terminated 
by LED serving as input for optically coupled 
line receiver. Logic 1 input is inverted to logic 
by inverter A, turning on Q, and turning off out- 
put of gate B. At same time, output of inverter 
A is logic 1, which inhibits turn-on of Qj and 
makes output of inverter D go low. Thus, logic 
1 input means that current is sourced into line 
and LED by Q,,then sunk by output of D. Simi- 
larly, logic input results in current being 
sourced into line by Q 2 and sunk by inverter B, 
making diode D, conduct and turn off LED of OCI 
receiver. — K. Erickson, Line Driver Is Compat- 
ible with OCI Line Receiver, EDN Magazine, Oct. 
5, 1976, p 106. 



1/6-7404 1/6-7416 



ISO 11200) (24001 



BIT-RATE GENERATOR— Fairchild 4702 IC syn- 
thesizes frequencies most often used in serial 
data communication, particularly with UARTS. 
With connections shown, output is 1760 Hz 
which is 16 x 1 10-baud rate of serial teletypes. 
Grounding only pin A generates 16 x 150 bauds. 
Grounding only pin B gives 16 x 300 bauds, 
grounding pin C gives 16 x 1200 bauds, and 
grounding pin D gives 16 x 2400 bauds. Will 
drive one regular TTL load at supply drain of 1 
mA.— D. Lancaster, "CMOS Cookbook," How- 
ard W. Sams, Indianapolis, IN, 1977, p 155. 




TOP VIEW 




SQUARE WAVE 
14 „ OUTPUT 



j. . V* TRIANGLE 

610 611 Q OUTPUT 



SIGNAL 




INPUT 




I 


Cc = Coupling Capacitor 


- 


Cb = Bypass Capacitor 



ANALOG 
O OUTPUT -i- 

(OPTIONAL! 



'I 



(V + = 12V to 24V) 



SINGLE-SUPPLY HIGH-PRECISION PLL— Com- 
bination of Exar XR-2207 VCO and XR-2208 op- 
erational multiplier is connected for operation 
from single 12-24 V supply for data communi- 
cation and signal conditioning applications. Op- 



erating frequency range is 0.01 Hz to 100 kHz. 
Timing resistor R„ should be in range of 5K to 
100K, and R, should be greater than R . For 10- 
kHz center frequency, C can be 0.01 j*F and R„ 
can be 10K. R, and C,, which determine tracking 



range and low-pass filter characteristics, are 
45K and 0.032 /xF.— "Phase-Locked Loop Data 
Book," Exar Integrated Systems, Sunnyvale, 
CA, 1978, p 62-64. 



258 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




o Output 



07H 



DIFFERENTIAL LINE RECEIVER— Responds to 
balanced-input drive signals fed to both com- 
parator inputs of 322. Output is undisturbed 
even with up to 1 V of common-mode noise on 
input lines. TTL-compatible output is in phase 
with positive input. Overall delay is about 1 
fis. — W. G. Jung, "IC Timer Cookbook," How- 
ard W. Sams, Indianapolis, IN, 1977, p 153-155. 



i 



» * — e > i 

;£: 0.2 uf ;feo.2 vf S;o.2 uF ;feo. 




*->w-*- 



t5V 

■o 



14V 

o 



10k 10k 10k 



:n 




''o.05t,F 



_n_n_ 



I) 0-5V 



c,"o.05 



ANALOG PLL IN FSK DEMODULATOR— Devel- 
oped for frequency-shift keying used in data 
transmission over wires, in which inputs vary 
carrier between two preset frequencies corre- 
sponding to low and high states of binary input 
signal. Circuit uses elaborate filter to separate 
modulated signal from carrier signal passed by 
PLL. 565 PLL provides reference for S710 com- 
parator. Article gives design equations. — E. 
Murthi, Monolithic Phase-Locked Loops — Ana- 
logs Do All the Work of Digitals, and Much More, 
EDN Magazine, Sept. 5, 1977, p 59-64. 



INPUT _|l_ 
SIGNAL ■ ■ 




SQUARE WAVE 
OUTPUT 

v\A 

TRIANGLE 
OUTPUT 



R2 

_ ANALOG OUTPUT 

"VVV f— O (OPTIONAL! 



T 



C2 



PLL FOR 0.01 Hz TO 100 kHz— Highly stable and 
precise phase-locked loop system using Exar 
XR-2207 VCO and XR-2208 operational multi- 
plier is suitable for wide range of applications 



in data transmission and signal conditioning. 
Supply voltage range is ±6 V to ±13 V. For 10- 
kHz center frequency, R is 10K and C is 0.01 
/*F. R 1 and C„ which determine tracking range 



and low-pass filter characteristics, are 45K and 
0.032 juF. — "Phase-Locked Loop Data Book," 
Exar Integrated Systems, Sunnyvale, CA, 1978, 
p 62-64. 



LINE DRIVER AND RECEIVER 



INPUTS 



TWISTED-PAIR TERMINATIONS— National 
DS7830 line driver applies digital data to 
twisted-pair transmission line in high-noise en- 
vironment, and DS7820 line receiver responds 



to data signals at other end of line while provid- 
ing immunity to noise spikes. Exact value of CI 
depends on line length. Supply voltage is 4.5 to 
5 V for both receiver and driver. C2 is optional 



C1 T 
0.002 M . 




OUTPUT 



STROBE *=T 



and controls response time. — "Interface Inte- 
grated Circuits," National Semiconductor, 
Santa Clara, CA, 1975, p 8-1-8-16. 



DATA TRANSMISSION CIRCUITS 



259 



23.89 k 
o— VW— 



:0.01 >211.7 k 



zfzo.01 S303.75 



1 



1 r ^ 34.28 
1/2 MC14B8 



=bo.01 S125.72 



<900.5 



i^>i^ k l |l M >U 

1/2MC1458 $ 0.01 nr^ Mn „, 



■1 1 



All capacitors are in t*F. 



BANDPASS ANSWER FILTER— Provides gain of 
15 dB over bandwidth of 1020 to 1320 Hz for 
low-speed modem system using Motorola 
MC6860 IC. Attenuation is 35 dB at 2225 Hz, as 
required for answer-only modem system. Equa- 
tions for values of filter components are 
given.— J. M. DeLaune, "Low-Speed Modem 
System Design Using the MC6860," Motorola, 
Phoenix, AZ, 1975, AN-747, p 10. 




son 



10-MHz COAX DRIVER— Provides high output 
current to coaxial line over bandwidth limited 
only by single-pole response of feedback com- 
ponents. Response is flat with no peaking and 
distortion is low. Uses Harris HA-2530/2535 
wideband amplifier having high slew rate. — 
"Linear & Data Acquisition Products," Harris 
Semiconductor, Melbourne, FL, Vol. 1, 1977, p 
7-54 (Application Note 516). 



-O 5V 




-O 5V 



100!! TWISTED PAIR LINE 



MULTIPLE DRIVERS MAy BE 
CONNECTED TO THE LINE 




WIRED-OR TERMINALS— Arrangement per- 
mits connecting several IC line drivers in parallel 
for feeding single 100-ohm twisted-pair data 
line. With wired-OR transmitting capability, TTL 



output of receiver at right is logic 1 only if all 
paralleled drivers are transmitting logic 1. H any 
one or all of drivers transmit logic 0, output of 



receiver is logic 0.— D. Pippenger, Termination 
Is the Key to Wired-OR Capability, EDNIEEE 
Magazine, Dec. 15, 1971, p 17. 



CLOCK 



MC10421 "1" 



MC14015 



C PS 

JAM INPUTS 



r*o s o 




MC 14507 



MC14507 




)E>- : 



SCRAMBLED DATA 
(WHEN "LOCKED"! 



PSEUDORANDOM CMOS— Uses MC14021 8- 
bft shift register in conjunction with MC14507 
EXCLUSIVE-OR gates to generate pseudoran- 
dom digital code. To develop code pattern, 1st, 
6th, 7th, and 8th bits are sent through EXCLU- 
SIVE-OR gates and fed back to shift-register 
input. Output can be used as random test signal 
or for protecting messages sent over public 



channels or stored in public files. Digital mes- 
sage is scrambled by mixing it with output of 
code generator in EXCLUSIVE-OR gate. Func- 
tionally identical 255-bit random generator is 
used at receiver to unscramble data. Decoding 
circuit must have access to sending dock and 
means for synchronizing so as to put both reg- 
isters into all-1 state. Register in receiver goes 



through all its states within 255 clock pulses; 
when it reaches all-1 state, signal is fed back to 
sender for releasing FF-1 so scrambling can 
commence. Article traces operation in detail. — 
J. Halligan, Pseudo-Random Number Generator 
Uses CMOS Logic, EON Magazine, Aug. 15, 
1972, p 42-43. 



260 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



SINGLE-SUPPLY LINE DRIVER— Motorola 
MC75451P driver and external components 
shown provide differential signal for twisted- 
pair transmission line from single +5 V supply. 
External gate provides required input phase re- 
versal to gate G2 of IC. Each output of IC varies 
between 0.5 V and 3.6 V, so net differential volt- 
age driven into line is about 6 V. Only receiver 
end of line is terminated in its characteristic 
impedance, since arrangement is intended only 
for point-to-point transmission. — T. Hopkins, 
"Line Driver and Receiver Considerations," Mo- 
torola, Phoenix, AZ, 1978, AN-708A, p 12. 




MC75107L 



MC75451P 




REMOTE DATA STATION— Circuit monitors DC processor. IM6100 remote host processor sends UART. Developed for use with Intercept Jr. mi- 
voltages applied to pins 19 and 20 of IH5060 control signals to IM6402 UART to select indi- croprocessor system.— S. Osgood, Remote 
multiplexer and converts them to digital format vidual multiplexer channels. Single 7209 oscil- Data Station Simplifies Data Gathering, EDN 
for transmission as serial data to remote micro- later provides clock signal for A/D converter and Magazine, Jan. 20, 1978, p 38 and 41 . 



CHAPTER 24 

Digital Clock Circuits 



Provide 12- or 24-hour time on LED, LCD, gas-discharge, or fluorescent digital 
displays for watches and clocks. Some also have calendar display and alarm- 
tone generator. Special circuits provide battery backup for AC power failure, 
multiplexing of display to reduce battery drain, stopwatch, and tide clock. 
Clock-pulse generators for logic and microprocessor applications are given in 
Clock Signal chapter. 




C l C 5 R s 

('/■MC14518) 



E ('/,MC14518) 



TrfmrtfimiTml= 



SPLIT/ .( 
(N.O.)^-| 



100k, V.Vf 



MODE. 



split! 

onqOnormal 

. 9nr 



sw 



MC14021) S, C 
C. Q. 




CONNECT TO CORRESPONDING COUNTER 



NORMAL 



P/S 



(MC14021) s 2 
l-|C. O. 



£ 



(MC14021) S 3 



p/si 



& 



7-SEGMENT LED 
DISPLAYS 



COLON IN 
DIS PLAY, 



I I I r+t 



"di 

I 



D,D 2 D 3 D 4 D 5 D 6 

(MC14021) S 4 

i-IC. Q. 



DECIMAL 



Ik, %WJ 
|\1 



1.5k, !4W, 



•BLANKING 
SW. 



DISPLAY 

Yblank 



uli Qir 

uuini 




-/*/V»- 



6-DIGrT STOPWATCH— Low-cost battery-pow- 
ered electronic stopwatch with 6-digit LED dis- 
play uses readily available complex-function 
CMOS ICs to minimize component count. Time 
range is up to 59 min and 59.99 s. Multiplexing 



by time-sharing counters through one display- 
driving decoder cuts battery drain because each 
digit is on for only one-sixth of time. Article 
traces operation of circuit step by step. Maxi- 
mum error is only 0.001 s'h. Four rechargeable 



nicad batteries last 500 h per charge if displays 
are blanked when not being read, and about 6 
h without blanking. — A. Mouton, Build Your 
Own Digital Stopwatch with Strobed LED Read- 
out, EDN Magazine, April 5, 1974, p 55-57. 



261 



262 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



^ 1 35V 



5 35pF : 




32. 768 H j 200k 



LCD WRISTWATCH— Inverter section of Intel 
5801 oscillator/divider is used with 32,768-Hz 
crystal to produce time base. First divider in 
5801 reduces this to 1024 Hz for driving upcon- 
verter transistor. Feedback from transistor 



through 12-V zener is used to regulate and con- 
trol pulse width of 1024-Hz signal. Upconverter 
also provides 12-15 V required by LCD and 5201 
decoder/driver IC. Output to each LCD segment 
and to common backplateis 32-Hz square wave. 



Separate drive flashes colon at 1-Hz rate. — M. 
S. Robbins, "Electronic Clocks and Watches," 
Howard W. Sams, Indianapolis, IN, 1975, p 128- 
130. 




.01 

-71- 



5K 

-wv- 



® 



12V 



fT 



-I 

r 



2 



POINT Hj PD..SECS 

A 60 .0167 

B 5 .2 

C 0.5 2 
D 24 

E 288 

F 10 



T 






ICI 
7492 



<D 



IC5 
7490 



© 



+ 5V 



IC2 
7490 



© 



+ 5V 



IC3 
7492 



© 



TO CLOCK 
J L 



& 



IK 
-Wv— 



120V 
60Hj 
(OR SHIP'S BATTERY) 



TIDE CLOCK— Circuit shuts off electric clock of 
any type for 5 s out of every 144 s, to give loss 
of 50 min in 24 h as required for making high 
tides conform to clock readings. Regulated 5-V 
supply shown drives TTL 7492 frequency divider 



that reduces 60-Hz linef requency by factor of 12 
to 5 Hz. 7490 divides this by 10 to give 0.5 Hz. 
Two more 7492s divide by 12 and 12 to give 
symmetrical pulses with period of 288 s. Second 
7490 divides 2-s pulse down to 10 s. Counter IC4 
inhibits 5-s counter by feeding low output into 
one gate of IC7 hex inverter. When IC4 counts 
up to 144 s, its output goes high and resets IC6 
to low for start of 5-s low period of that counter. 
Article gives timing waveforms. Switching tran- 
sistor is used to control relay that opens clock 




circuit. Set tide clock at 12:00 for high tide at 
location of use, and ft will be 12:00 at high tide 
thereafter. Low tide will then be at 6:00. — J. F. 
Crowther, Time and Tide — Digitally, 73 Maga- 
zine, Aug. 1978, p 156-157. 



DIGITAL CLOCK CIRCUITS 



263 



SPRAGUE UHP-491 




12-h WITH SECONDS— Combination of Mostek 
clock IC and Sprague high-voltage display driv- 
ers, acting through 206C and 216C single in-line 
resistor network, provides drive for conven- 
tional seven-element gas-discharge digital 
clock display showing hours, minutes, and sec- 
onds. Requires -200 V supply. Display can be 
Burroughs Panaplex, Cherry Plasma-Lux, or 
Beckman SP series.— "Integrated Circuits Data 
Book— 1," Sprague, North Adams, MA, 1978, p 
3-5. 




-— I3AG,Z50VMAMP 



eludes snooze alarm along with regular built-in 
6-DIGIT WITH CALENDAR AND ALARMS— Cir- outs. Transistor switch Q1 and relay form timer transistor-driven buzzer.— M. S. Robbins, 
cult is built around Cal-Tex CT7001 IC that in- triggered by IC to control radio or other appli- "Electronic Clocks and Watches," Howard w! 
eludes outputs for displaying day of month ance drawing up to S A from AC line. Dual-volt- Sams, Indianapolis, IN, 1975, p 103-104 and 
along with time on Utronix DL707 LED read- age power supply provides 7 and 14 VDC. In- 116-117. 



264 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




5=25 pF 



92CS-2I5J2 



2-MHz CRYSTAL USING CMOS PAIR— One Low power drain makes circuit ideal for use in 

CMOS transistor pair from CA3600E array is digital clocks and watches.— "Linear Integrated 

connected with feedback pi networktogivesta- Circuits and MOS/FET's," RCA Solid State Divi- 

ble oscillator performance with 2-MHz crystal, sion, Somerville, NJ, 1977, p 280. 




ALARM FOR DIGITAL CLOCK— Uses transistor 
as driver to turn on programmable unijunction 
transistor (PUT) oscillator feeding 8-ohm loud- 
speaker. Pitch of tone can be adjusted with 10K 
pot. Input is from alarm pin of digital clock IC 
(pin 3 for Fairchild FCM7001 equivalent of Cal- 
Tex CT7001). PUT is Radio Shack 276-119 or 
equivalent.— W. J. Prudhomme, CT7001 Clock- 
buster, 73 Magazine, Dec. 1976, p 52-54 and 
56-58. 




irLEDIO 



i Fn 


— LED 6 


10 AAR 


SWI 


"-SW! 


PUSH-BUTTON SW 


LED 7 — -LEDIO RL50 


Dl— 


-04 


N4003 


05 


N9I4 




ICI 


MMS3I3 


2N2907 
TIS98 


QI3- 


-0I9 



Tl IOVA.C. C.T. 

RESISTOR VALUES IN OHMS 

ALL RESISTORS ARE I/2 W 5X 



6-DIGIT LED WITH SLEW BUTTONS— National 
MM5313 PMOS digital clock IC drives display 
which includes four discrete LEDs mounted on 
readout panel to form colons between hours, 
minutes, and seconds. AC supply provides 14 



VDC for IC and 7 VDC for displays. Hold push- 
button SW1 stops count to give precise seconds 
setting. Slow-slew button SW2 advances time 
at 1 min/s for precise setting, and fast-slew but- 
ton SW3 advances time 1 h/s. Digit drivers Q1- 



Q12 are Darlington-connected pairs of PNP tran- 
sistors. Segment drivers Q13-Q19 are single 
PNP transistors.— M. S. Robbins, "Electronic 
Clocks and Watches," Howard W. Sams, Indi- 
anapolis, IN, 1975, p 103 and 113. 



DIGITAL CLOCK CIRCUITS 



265 




100 k 

VodO-vs/v- 



/2-MC14011 

f J G2 JO 

1MHz 


1/2-MC14518 

E Q4 

R.C 



100 k 



ill 



X 



1/2-MC14518 
E Q4 



Fast 
Set 




Slow 
Set 



1/2-MC14518 



TT 



j1 kHz Multiplex 
Rate 



1/2-MC14518 



Q4 



1/2-MC14518 
E Q4 

R.C 




MC-14518 

E Q4 

R.C 




„.„ -L 




J_ 



To Clock 

Input 



1-Hz REFERENCE— Output of 1-MHz crystal os- 
cillator is stepped down to 1 Hz by CMOS de- 
cade divider chain using Motorola MC14518 
dual decade counters. Circuit also generates 1- 
kHz multiplex rate for display used with 24-h in- 
dustrial clock. Supply is +5 V. — D. Aldrkfge and 
A. Mouton, "Industrial Clock/Timer Featuring 
Back-Up Power Supply Operation," Motorola, 
Phoenix, AZ, 1974, AN-718A, p 5. 



1/4-MC14001 



LIQUID CRYSTAL DISPLAY 

OR 

FLUORESCENT TUBES 



BATTERY 




GND O 
IGNITION C* 

SI OPEN LC DISPLAY 

AUTO CLOCK— National MM5377 chip for au- S1 CLOSED FT DISPLAY 

tomobile clock interfaces directly with 4-digit colon indication. Voltage-sensitive output erence time base.— "MOS/LSI Databook," Na- 

liquid-crystal or fluorescent-tube display. 12-h drives energy-storage network serving as volt- tional Semiconductor, Santa Clara, CA. 1977, p 

format includes leading-zero blanking and age doubler/regulator. Crystal oscillator is ref- 1-33-1-37. 



266 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




m 



R2 
R3 



_S3 



34 28 30 36 35 33 32 37 31 29 8 13 12 11 10 14 9 1 6 5 4 3 7 2 
16 V SS 



40 V DD 

27 MIN/DATE SET 



38 SEC/DATE 

DEM & 18 

START | Kl 



IC 

MCI 4440 

Digital Watch w/Calendai 



17 25 20 

OUT HF HF 



19 
Displ 39 

TST V SS 



Crystal 
Oscillator 



32.768 kHz 



C5j^. X1 C4 

6 35 |,F ^ 20 pF ^ 




v 0.05nF 



1 .5-V LCD — Will operate over 1 year on single 
1.5-V AAA battery with accuracy of ±1 min. 
Basic timekeeping functions are provided by 
Motorola MC14440 CMOS device that includes 
calendar. 32.768-kHz NT-cut quartz crystal and 
trimming capacitor provide reference fre- 
quency. Output of 1 .5-V alkaline cell is increased 
to 4 V for display by voltage tripler using 
MBD101 Schottky diodes. — J. Roy and A. Mou- 
ton, "A Cordless, CMOS, Liquid-Crystal Display 
Clock," Motorola, Phoenix, AZ, 1977, EB-56. 




GAS-DISCHARGE DISPLAY— National MM5309 gas-discharge display having colon and AM/PM "MOS/LSI Databook," National Semiconductor, 
digital clock gives choice of 12- or 24-h display indications. Separate cathode driver and sepa- Santa Clara, CA, 1977, p 1-2-1-8. 
and 50- or 60-Hz operation for driving 4-digft rate anode driver are required for each digit.— 



DIGITAL CLOCK CIRCUITS 



267 



Vdd 



,i§>j£S> 



CIRCULAR LED ARRAY— Arrangement of 60 
LEDs sequencing in outer ring to indicate sec- 
onds and minutes, combined with 12 in inner 
ring to indicate hours, is driven by Motorola 
MC14566 CMOS industrial time-base generator. 
Time reference is 16.384-kHz crystal oscillator 
consisting of two NOR gates and Statek crystal. 
Reference frequency is divided by 2" in U2 to 
give 1-s pulse rate for driving accumulators 
U3A-USB. Maximum error is 1 s per month. U3 
counts seconds, U4 minutes, and U5 hours. 
Multiplexing is required because same set of 60 
LEDs serves for minutes and seconds. Fast and 
slow touch pads eliminate need for switches 
when setting time. Single 12-V nicad battery 
provides backup for AC line failure.— A. Mou- 
ton, "The LED Circular Timepiece," Motorola, 
Phoenix, AZ, 1975, EB-41. 




DL-10A 



















1 












1 




A 


3 C D E 


- o 






1 


















































* 
















— — 1 


1 — •» 



TO DIGIT LINES 



TO SEGMENT LINES 



MULTIPLEXED CLOCK DISPLAY— Multiplexed 
display suitable for LED readouts is provided by 
circuit using TTL counters to count 60-Hz line. 
When count reaches 10 o'clock, flip-flop M is set 
on every cycle. Gate G 3 then detects when time 



goes to 13 o'clock, and clears shift register. 
Carry flip-flop remains set, so 1 is loaded into 
hours digit to accomplish transition from 
12:59:59 to 1:00:00. Seven-segment decoder 
driver looks at shift register output and drives 



segment lines of LED. Leading hours digit is 
blanked, using RBI input on 9317. — G. Smith, 
Novel Clock Circuit Provides Multiplexed Dis- 
play, EDN Magazine, Sept. 1, 1972, p 50-51. 



268 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




60H* 

TO CLOCK 




STANDBY SUPPLY— Phase-shift oscillator Q1 
operates from AC line through bridge-rectifier 
power supply and provides line-synchronized 
60-Hz power to standard digital clock through 
isolating emitter-follower 02. During power 



outage, oscillator is switched automatically to 
battery by diode network and provides reason- 
ably accurate signal for operating clock. Free- 
running oscillator is adjusted to be slightly low, 
such as 59.9 Hz. For reasonably long power out- 



age, say 4 h, this 0.1-Hz error is equivalent to 
0.167% error in time, so clock loses only 24 s 
during outage. CI and C2 are 200 to 300 juF. Ad- 
just R1 to give output just below 60 Hz on bat- 
tery operation. To minimize battery drain, LEDs 
on digital clock are not energized during 
standby. — R. S. Isenson, Digital Clock Fail-Safe, 
73 Magazine, July 1977, p 168-169. 




IGNITION 



12-V WITH GAS-DISCHARGE DISPLAY— Na- 
tional MM5379 automobile clock package inter- 
faces with standard 4-digit gas-discharge dis- 
play. Format is 12 h with leading-zero blanking 
and colon indication. 2-MHz crystal provides 
time accuracy. — "MOS/LSI Databook," Na- 
tional Semiconductor, Santa Clara, CA, 1977, p 
1-38-1-42. 



DIGITAL CLOCK CIRCUITS 



269 



CAPACITOR 
REQUIRED 
TO SUPRESS 
LINE NOISE 




I . 100k 0.02b 



FREQUENCY V„ 
ELEMENT 



DIGIT / 3 



CLOCK CHIP DR | VERS \ t 



SEGMENTS 



F S H 

A L 

50/60 Hr SOL 4/6 

INPUT T W D D IGIT ibcdelj 
_ f 



-30pF 1 



— «Q« — " 



jgjffi ffl ffl (®|© 



500|)F 



- 2S0kH? T 

CRYSTAL 
OSCILLATOR 




LEVEL 
TRANSLATOR 



AC/DC CLOCK— When AC power fails, MCD-2 
optoisolator senses voltage drop and makes 
Schmrtt trigger force strobe input of clock chip 
to ground, blanking display and reducing cur- 



rent '' 3in from 200 mA on AC to 12 mA on 9-V 
standby battery. Clock will run for days on 1000- 
mAh battery. Two LED pairs that form colons 
between time digits are operated from digit 



strobe lines and remain lit when display is 
blanked, but draw only 1 mA. — S. I. Green, Dig- 
ital Clock Keeps Counting Even When AC Power 
Fails, EDN Magazine. Dec. 20, 1974, p 49-51. 



~40-0HM SPEAKER 




51 fast set input 

52 slow set input 

53 seconds display input 

54 alarm display input 

55 sleep display input 



S6 
S7 
S8 
S9 



alarm off input 
snooze input 
alarm tone on/off 
alarm output on/off 
tone amplitude control 



DIGITAL ALARM— Direct drive offered by Fair- 
child 3817 IC allows design of simple low-cost 
clock radio providing display drive, alarm, and 
sleep-to-music features in 12- or 24-h formats. 



Display is Fairchild FND500 LED. Either 50- or 60- 
Hz input may be used. U2 is 7800-series IC volt- 
age regulator rated to meet requirements of 
radio used. Q3 provides active low output for 



timed radio turnoff after user-selected interval 
of up to 59 min. CR4 and C5 rectify alarm-tone 
output for amplification by Q4 to give active low 
output for timed radio turn-on when coinci- 
dence is detected by alarm comparators. Q5 
provides alarm-tone output at level sufficient to 
drive 40-ohm loudspeaker with ample wake-up 
volume. If radio is used, omit loudspeaker. Ar- 
ticle covers construction and adjustment. — D. 
R. Schmieskors, Jr., Low-Cost Digital Clock, 
Ham Radio, Feb. 1976, p 26-30. 



270 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



BATTERY 
1.3V -*■ 
or 1.5 V T 




r-^.0 



ROTOR 



I MOTOR ■ 

MTM1 orMTM2 



WATCH 
MOVEMENT 



C v = Trimmer capacitance 

C 0UT = Integrated oscillator output capacitance 

^20pF 
R FB = Integrated oscillator feedback resistance 

*40M 

QUARTZ-MOTOR WRISTWATCH — Uses one motor at output of chip for driving conventional buffers. — B. Furlow, CMOS Gates in Linear Ap- 
32.768-kHz crystal at input of Motorola MTO watch hands. Chip contains three-inverter os- plications: The Results Are Surprisingly Good, 
160F or 161F custom CMOS chip, with stepper cillator, 16 counting flip-flops, and motor drive EDN Magazine, March S, 1973, p 42-48. 



RG 
300 W» 



10 HOURS 
HOURS A 




12-V AUTO CLOCK— National MA1003 auto- 
motive/instrument clock module combines 
MM5377 MOS LSI clock with 4-digft 0.3-inch 
green vacuum fluorescent display, 2.097-MHz 
crystal, and discrete components on single 



*Z1-MM5377 



printed-circuit board to give complete digital 
clock. Brightness control logic blanks display 
when ignition is off, reduces brightness to 33% 
when parking or headlight lamps are on, and 
follows dash-lamp dimming control setting. 



x: 



FILAMENT (-) 

3 



B4 

C4 

A3 

83 

C3 

03 

E3 

F3 

G3 

COLON 

B2 

C2 

02 A2 

E2 

F2 

G2 

A1 

Bt 

C1 

D1 

E1 

F1 

CI 



Display has leading-zero blanking. For portable 
applications, display can be activated by closing 
display switch momentarily. — "MOS/LSI Data- 
book," National Semiconductor, Santa Clara, 
CA, 1977, p 13-8-13-10. 



DIGITAL CLOCK CIRCUITS 



271 



Vss 

1 



MO Hi 
INPUT 



1111 



S, S 10 M, M 10 H, H„ 



DIGIT SELECT v. 



FREQUENCY MM4311/MM5311 SERIES 
ELEMENT DIGITAL CLOCK 



SEGMENT LINES V ° D 



HOLD SLOW FAST 



FTT 



i. 



? 



2N4403 OR 
EQUIVALENT 



HOURS 
ID'S 
DIGIT 



DMI8B3 



SECONDS 
IS 
DIBIT 



-vw- 

12 — VW- 
14 — WV- 

16 — WV- 



MAN1A0R 
EQUIVALENT 



6-DIGIT DISPLAY— National DM8863 8-digit 
LED driver serves as segment driver for com- 
mon-anode display of hours, minutes, and sec- 
onds, replacing total of 14 resistors and 7 tran- 
sistors.— C. Carinalli, "Driving 7-Sagment LED 
Displays with National Semiconductor Cir- 
cuits," National Semiconductor, Santa Clara, 
CA, 1974.AN-99, p11. 



SUBS 



fl* - 200. VARIABLE DEPENDING ON DESIRED DISPLAY BRIGHTNESS. 



220 V 



^ 100k 
-T> VV\r- 



£ t t i 1 

-© © — 




AC DIGITAL CLOCK WITH STANDBY BAT- 
TERY— Uses MM5316 alarm-clock IC, originally 
designed to drive LCD or fluorescent displays, 
but modified here for LED display. Diodes and 
batteries provide power if AC fails, with blank- 



ing of display to extend battery life. Accuracy is 
poor on batteries but batteries make resetting 
of time and alarm easier after AC interruption. 
Alarm uses 555 multivibrator to produce fre- 
quency-shift warble on output tone. Time is set 



by fast and slow buttons, and alarm is set with 
same buttons while depressing alarm-display 
button. Transistor type is not critical.— M. F. 
Smith, Digital Alarm Clock, Wire/ess World, 
Nov. 1976, p 62. 



272 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




DIGITAL WRISTWATCH— Single Intersil 
ICM7200 IC drives multiplexed display giving 
choice of hours and minutes, seconds, and day/ 
date. CMOS chip divides 32.768-kHz crystal out- 
put in long internal binary divider to produce 
basic 1-s clock rate. Further division gives other 



elements of display. Pressing read button once 
gives hours and minutes; pressing second time 
gives day and date; and pressing third time 
gives seconds. — D. Lancaster, "CMOS Cook- 
book," Howard W. Sams, Indianapolis, IN, 1977, 
p 377-378. 




BATTERY BACKUP — During normal operation, 
all power for digital clock is provided by AC 
power supply. During power failure, clock con- 
tinues operating from battery backup using two 
9-V batteries in series. Battery drain is limited 
by diode CR2 that blocks power flow to dis- 
plays. Optional switch may be installed across 
diode to short it for momentary viewing of dis- 
play. — W. J. Prudhomme, CT7001 Clockbuster, 
73 Magazine, Dec. 1976, p 52-54 and 56-58. 



ALARM SELECT 

ALARM DISPLAY/SNOOZE 
■4 BRIGHTNESS CONTROL 




ALARM 
AND 
MUSIC 



ALARM BUZZ 
ITO AUDIO 
STAGE! 



4-DIGIT 0.7-INCH LED DISPLAY— National 
MA1013 clock module contains MOS LSI clock 
IC, display, power supply, and associated dis- 
crete components on single printed-circuit 
board that is easily connected to radio. Oper- 



RADIO 
GROUND 



ates from either 50-Hz or 60-Hz inputs, and gives 
either 12- or 24-h display format. Nonmulti- 
plexed LED drive eliminates RF interference. 
Display is flashed at 1-Hz rate after power failure 
of any duration, to indicate need for resetting 



clock. Zero appearing in first digit is blanked. On 
12-h version, dot in upper left comer is ener- 
gized to indicate PM.— "MOS/LSI Databook," 
National Semiconductor, Santa Clara, CA, 1977, 
p 13-23-13-28. 



DIGITAL CLOCK CIRCUITS 



273 



EVEREADY 
513E 



EVEREADY 

513E " i.5v 



EVEREADY 



513E 




4-h DIGITAL WATCH— Single Motorola MC 
14521 CMOS IC drives single-digit MAN 3 LED 
display in such a way that time range of 4 h is 
obtained with 1.875 min resolution. Can be built 
into old watch case at cost under $10 for parts. 
Oscillator frequency of 1.165 kHz can be 
tweaked to adjust clock, or crystal oscillator can 
be added for high accuracy. Analog/binary for- 
mat of readout provides deciphering challenge 
to user, even though article gives diagram 
showing which segments of LED are lit for each 
time reading. Time intervals represented by 
each lit segment of display are: B = 2 h; C = 1 
h; A = 30 min; F = 15 min; G = 7.5 min; E = 
3.75 min; D = 1.875 min.— R. M. Steimle, Small 
CMOS Digital Watch Has Analog LED Output, 
EON Magazine, Aug. 20, 1976, p 86. 




12-h ALARM-General-purpose digital clock vide drive for alarm. Brightness control is op- "MOS/LSI Databook," National Semiconductor, 
with alarm uses National MM5402 or MM5405 tional. Sleep output can be used to turn off radio Santa Clara, CA, 1977, p 1-68-1-73. 
MOS IC to drive 3Vdigft LED display and pro- after desired time interval of up to 59 min.— 



274 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




I 4 



5volts 



O- 



1K 

■AAAr- 



7 8 



2 555 



6) 



;01 U F 



+, ,10uF 



IK T 10K 
'A/Wi-^WV- 



M 



to pin 3 of 
CT7001 



ALARM GENERATOR— Simple 555 timer gen- 
erates alarm tone driving small loudspeaker, for 
use with Cal-Tex CT7001 and other similar dig- 
ital clocks which do not have internal tone gen- 
erator. Circuit requires +5 V, but supply can be 
higher value if suitable dropping resistor is 
used. — M. S. Robbins. "Electronic Clocks and 
Watches," Howard W. Sams, Indianapolis, IN, 
1975, p 91. 



0-9 s DIGITAL READOUT— Can be used for 
classroom demonstration of digital logic driv- 
ing 7-segment LED or as attention-getting desk 
display ~'me base Q1 feeds sequential timing 
pulses to 7490 decade counter. Pulses are 
counted in binary mode, and bit pattern corre- 
sponding to digits 0-9 is fed to 7447 binary-to- 
decimal decoder/driver connected to 7-segment 
readout. Calibrate with watch or with timing 
reference signals from WWV, adjusting R1 so 
display advances 1 digit per second. — F. M. 
Mims, "Electronic Circuitbook 5: LED Projects," 
Howard W. Sams, Indianapolis, IN, 1976, p 72- 
75. 



5. 5-V DC 

COMMON ANODE 

ONLY 

o 




COMMON CATHODE 
ONLY 



R4-R10 


SEGMENT CURRENT 


370 n 


10 mA 


185 


20 mA 



eoHi s ^ 




SIMPLE 24-h CLOCK— Use of 60-Hz power fre- 
quency as time base simplifies design while still 
giving long-term accuracy comparable to that 
of crystal time base. Four-digit display uses 
Hewlett-Packard 5082-7340 displays requiring 
only simple four-line BCD input. National 
MM5312N IC divides line frequency down to 



one pulse per minute and advances its internal 
storage register at same rate. Output of register 
is in binary form at pins 1, 2, 3, and 24, synchro- 
nized with digit-enable outputs at pins 18, 19, 
20, and 21. Binary data is thus applied to all four 
displays in parallel, with enable lines controlling 
data feed. SN7404N inverter converts binary 



output data to TTL level required by displays. 
Power supply provides +5 V and -12 V for ICs 
anH 60-Hz reference for clock check. CR5 is 
Radio Shack 276-561, CR6 is 276-563, and CR1- 
4 are 276-1146.— K. Powell, 24-Hour Clock with 
Digital Readout and Line-Frequency Time Base, 
Ham Radio, March 1977, p t 



DIGITAL CLOCK CIRCUITS 



275 



LCD1 



» DO i_i 



ALWAYS ON 
TERMINAL 



LIQUID 

CRYSTAL 

DISPLAY 




117v. 
60 Hz 



C2 

.05 



2-INCH LCD NUMERALS— Uses C1200 clock IC 
made by LSI Computer Systems, having time 
set, logic, division for seconds, minutes, and 
hours, 7-segment decoding, and display drivers 
and switches. Four-digit liquid crystal display 
panel (LCD) is MGC-50. SI and S2 advance min- 
utes or hours on display at 2-Hz rate for setting 
time. To use as elapsed-time indicator, close S1 
and S2 simultaneously to generate reset pulse 
that sets timing change to zero. When both 
switches are released simultaneously, time 
count starts from zero. — R. F. Graf and G. J. 
Whalen, A Giant LCD Clock, CQ, Feb. 1978, p 18- 
23 and 76. 



DIVIDE BY 5000 FOR CLOCK— Counter chain 
uses CD4017 that divides by integer from 2 to 
10, selected by connecting appropriate output 
to reset. Extra gates recommended by RCA are 
not needed. Used in digital clock that changes 
automatically to battery operation when AC 
power fails. Clock operates on either 50 or 60 
Hz.— S. I. Green, Digital Clock Keeps Counting 
Even When AC Power Fails, EON Magazine, 
Dec. 20, 1974, p 49-51. 



INPUT,. 

fL 14 

(250kHz) 



«GL 



CLOCK 
CLOCK 
ENABLE 



16 



RESET 5 V„ 



OUT 



CD4017 

+5 



TOV„ 



3 14 



£L 



16 



OUT 



16 



3 2 



CD4017 
-5-10 



sQ 



CLOCK OUT 



13 l B| 13l 8| iH 



'|8|9|15| 



OUTPUT! 
14 ^ 



150 Hi) 



MC14518 
-MOO 





dtfetJt 



<5- 



TO SP 332 
22K £ £ 22K SEGMENTS 

(IF USED) 



O200VI -V O- 



•(X4) FOR HRS, MINS. (X6) FOR MRS. MINS. SECS 



4-DIGIT GAS DISPLAY— CMOS clock IC drives 
multkJig'rt gas-discharge display. Simple circuit 
does not include alarm, flashing colon, and AM/ 
PM features. Seven segment-driver circuits and 



four digit-driver circuits are required, although 
only one of each is shown. Additional drivers 
are needed if seconds display is desired. Re- 
quired supply voltages can be obtained from 



transformer-type supply driving diode bridge; 
regulation is not needed. — M. S. Robbins, 
"Electronic Clocks and Watches," Howard W. 
Sams, Indianapolis, IN, 1975, p 68-71. 



276 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



100k f 




BATTERY BACKUP — Four nickel-cadmium bat- 
teries connected in series provide automatic 
backup for 5-V supply of digital clock. Under 
normal AC line operation, battery is continually 
being recharged with half-wave rectified and 
unfiltered supply that allows internal chemical 
reactions to settle between pulses of charging 
energy. R1 is chosen to make average charging 
current about 5% of battery rating. — D. Ald- 
ridge and A. Mouton, "Industrial Clock/Timer 
Featuring Back-Up Power Supply Operation," 
Motorola, Phoenix, AZ, 1974, AN-718A, p 7. 



1N2070 



12- OR 24-h CLOCK — Single American Micro- 
systems AMI S1736 clock chip drives liquid- 
crystal readout to give either 12-h display with 
AM/PM indicator or 24-h digital display by 



changing only three connections. — LSI in Con- 
sumer Applications, Round 2: Clocks on a Chip, 
EDN Magazine, May 5, 1973, p 22-23. 



COMMON CATHODE LEDS 

(DL704 OR EOUIV) 
HRS/MOS MINS/DAYS SECONDS 



I 1 = 1 I 



DIGIT DRIVER DETAILS: 0UTpuT 
ALT NO I: 



(6 REQUIRED) 



A- 



L. 



Dl INPyT__J7K 
vw 




A L T NO 2 : Dl D2 03 04 OS D6 

nilTPLJTS —Hl2l6|7| 9 1 131 



I4l 3l 5l8ll0ll2l 
INPUTS - Dl D2 D304 Di D6 



ALL DIODES ARE IN914 




12.6 VAC 

60H2 INPUT 



CALENDAR CLOCK— Uses Fairchild FCM7001 IC 
equivalent of Cal-Tex CT7001 clock chip (which 
is no longer available) to drive six 7-segment 
LEDs that can be switched to show 12- or 24-h 



time and 28/30/31 calendar, along with alarm 
features. Article gives construction details. 
Each SN75491 driver chip has pins 3, 5, 10, and 
12 connected to pin 11 through 150-ohm resis- 



tor. RL is typically 2.7K, chosen to limit LED cur- 
rent to less than 5 mA. — W. J. Prudhomme, 
CT7001 Clockbuster, 73 Magazine, Dec. 1976, p 
52-54 and 56-58. 



CHAPTER 25 

Display Circuits 



Drives and controls for LEDs used singly or in arrays, as well as liquid crystal, 
gas-discharge, fluorescent, incandescent, bar-graph, and Nixie displays. 
Includes controls for brightness, zero-suppression, strobing, and multiplexing. 
For displays on cathode-ray screens, see Cathode-Ray chapter. 




Only needed if minimum I [33 is required 



FLUORESCENT DISPLAY DRIVER— National oscillator for supplying clock signals to MOS enable input provides ghost-free display.— "In- 

DS8881 vacuum fluorescent display driver han- circuit, filament-bias zener, and 50K pulldown terrace Databook," National Semiconductor, 

dies 16-digit grids. Decode inputs select 1 of 16 resistors for each grid. Outputs will source up Santa Clara, CA, 1978. p 5-57-5-60. 

outputs to be pulled high. Driver also contains to 7 mA. Supply is 9 V. Interdigit blanking with 

277 



278 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



LM339 



ANALOG INPUT 1 

(0 - 2V) 



ANALOG INPUT 2 

(0 - 2V) 



•USED ONLY TO KEEP 

RESET CATHODE 

SEGMENT GLOWING 




230V 



-* KEEP ALIVE ANODE 



-► ANODE 1 



-► AN0OE2 



100k 
CALIBRATION 



All resistors 1/4W except as specified. 



,0k aiV* 33k 09t^ 33k aioK* 

I VW 1 MPSL01 I WV 1 MPSL01 I W\f— I IWPSL01 



KEEP ALIVE 
-5V I CATHODE 



r 



RESET 
CATHODE 



PHASE 1 



PHASE 3 



BAR-GRAPH DRIVE— Use of National LM339 
quad comparator minimizes number of com- 
ponents needed to drive Burroughs 200-seg- 
ment gas-discharge bar display. Every third 
electrode of display is tied together, so only 
three lines (phase 1, 2, and 3) control all seg- 
ments. When phase lines are driven by consec- 
utive pulses, glow of gas-discharge element is 
propagated continuously along array. Anode 



voltage is gated so number of glowing seg- 
ments is proportional to analog input. Compar- 
ators A1 and A2 generate gated anode signals 
with durations proportional to inputs. A3 com- 
pares ramp signal to 2-V reference and gener- 
ates end-of-scan signal when ramp exceeds ref- 
erence. A4 generates clock having period of 
about 60 jus. — S. N. Kim, "Driving Burroughs' 
Bar Graph Display," National Semiconductor, 
Santa Clara, CA, 1975, DB-4. 



DISPLAY CIRCUITS 



279 



AUTOMATIC BRIGHTNESS CONTROL— Circuit 
adjusts brightness of LED digital display by al- 
tering mark-space ratio of LED supply voltage. 
Ambient-light input is sensed by BC109C tran- 
sistor with top taken off . Normal display current 
of 20 mA is reduced to 2 mA when darkened 
room makes brightness unnecessary, conserv- 
ing battery life. Tr 3 and Tr 4 operate as Schmitt 
trigger, with mark time of 1 .5 ms determined by 
R 2 and space time controlled by charging cur- 
rent through Tr 5 and Tr 2 as affected by ambient 
light on Tr,. Article gives complete circuits for 
driving 11-LED array. To add brightness control 
circuit, break ground connection of LED supply 
transistors and insert saturated transistor Tr s .— 
G. Kalanit, Analogue to Digital Meter, Wireless 
World, July 1976, p 53-57. 




MC14013 Dual D 



T 




BCD 
From Latches 
/ 



MO V 
9 



Dl 

*— *— w- 



(2/61MC14572 100 pF 0.01 MF . MSD70Q0 



4> 

U^ + iov 



(1/6) MC14572 



Scan Oscillator 
f. => 3 kHz 



Display Protection 



L 



A MC14511 

B i 

c BCD to 
p 7-Segment 

Latch/ 
Decoder/ 

Driver 



LT 
LE 



T 



18 k 



18 k 
— \^— 




To MC14S08 
Dual 4 Bit Latches 



3.3k 
— w^— 



+ 10 V 

o 



R5 
10k ! 



■c 



< 



MPS U95 
Q1 

* 



■c 



MPS-U95 
Q4 



(4) DR2110 

Numetron 



MSD y c 



-> LSD 




3.3k 

-Wr- 



(28) 1N914 D22 



2N4400 
Q11 



tZZl r^ ^ ~^T 'IT? 8 , * '"" mA Per S69ment Wh6n direct - drive "; with -"«'■ Prevent high peak current from degrading dis- 

£nS£3™i 9 « mUlt 'P ,exed ™ i9it in " ti P lexin 9' i"«antaneous power must be 9 V at piay when applied continuously to 1 digit -A. 

candescent d,splay. Scan decoder requ.res only 48 mA to maintain same average power per seg- Pshaenich, "Interface Considerations for Nu- 

two input NAND gates since blanking is not re- ment. Display protection circuit monitors scan meric Display Systems," Motorola, Phoenix 

qu.red.lncandescentdisplayrequires4.5Vat24 oscillator and blanks display if oscillator fails, to AZ, 1975, AN-741, p 25. 



280 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




10V 



* USE TWO 2NWt OR 2N2222 
TO MAKE A DARLINGTON 
TRANSISTOR. 

BAR-GRAPH READOUT— Transistors switch 
row of LEDs on in succession to give rising-bar 
display indicating input voltage. R2 can be ad- 
justed from minimum range of 0.1 to 0.5 V in 
0.1-V increments for five LEDs to maximum of 



R3, RS. R7. R9, RU ■ 10K 
R4. R6. R8.R10.Rl2- 22055 
Q2-Qf> • 2N}'XK OR 2N2222 

1 .0 to 1 0.0 V in 1-V increments. Input resistance 
of circuit is above 100,000 ohms. — F. M. Mims, 
"Electronic Circuitbook 5: LED Projects," How- 
ard W. Sams, Indianapolis, IN, 1976, p 86-88. 




SEGMENT 

SELECT 

LINES 



SIX 

DIGIT 

CALCULATOR 



DIGIT 

SELECT 

LINES 



"X 




11 

3 

5 

10 

12 

DM75491 

1 2 

7 6 

8 9 

14 13 

4 



± 



mm 



DP 



SEGMENT 

ENABLE 

LINES 



»O b o o 

<lJLh U. U. 






± 



o o o 

/_/. u. /_/. 



1_£ 



D5 



REDUCING LED POWER DRAIN— Arrangement 
of LEDs in groups of four with constant-current 
source greatly eliminates wastage of battery 
power. Circuit shows utilization of this tech- 
nique to display 4-bit binary number from 
CMOS counter.— T. R. Owen, L.E.D. Display, 
Wireless Work/, June 1976, p 72. 



6-DIGIT DRIVE— Uses two National DM75491 
four-segment drivers for multiplex-mode dis- 
play of MOS calculator. Total of eight segment 
drivers provides drive for each one of seven seg- 
ments plus logic control for decimal point. — C. 
Carinalli, "Driving 7-Segment LED Displays with 
National Semiconductor Circuits," National 
Semiconductor, Santa Clara, CA, 1974, AN-99, 
p9. 



6 7 

DM75492 
5 8 



DIGIT 

ENABLE 

LINES 



1 



•CURRENT LIMIT RESISTORS 
•NSN33 OR EQUIVALENT 



DISPLAY CIRCUITS 



281 




BCD DECODER— Radio Shack RS7447 BCD to 7- 
segment decoder converts settings of four BCD 
input switches to corresponding 0-9 digit on 7- 
segment common-anode LED display. Display 
is Radio Shack 276-053. Battery can be four AA 



DISPLAY: STANDARD 
DIP PIN SPACING 

cells in series, with 1N914diodeinserted in pos- 
itive lead to reduce voltage to 5 V. — F. M. Mims, 
"Integrated Circuit Projects, Vol. 2," Radio 
Shack, Fort Worth, TX, 1977, 2nd Ed., p 27-40. 



+ 10to20V 




LED BRIGHTNESS CONTROL— Uses 10K loga- 
rithmic pot to vary brightness simultaneously 
for all LEDs in digital display.— S. F. Bywaters 
and J. E. West, Peak-Reading Audio Level Indi- 
cator, Wire/ess World, Aug. 1975, p 357-361. 




5) SI Se Sd Sc Sb S> v s 

MMSJ36 
01 02 03 D« OS 06 «ci 



KEYBOARD 

6-DIGiT LED DRIVER— National DS8877 driver 



4701! 

-vw— 



MIH6040B_Zi.» llu 
EOUiV X. 



!• Sb St Sd Sa Si S| 

o p O O O O " ,SA,,M 

u u u o. o o 



X 



POWER 
SWITCH 



\ 



is shown in configuration for use with 6-diait Driver requires no standby power and operates tabook," National Semiconductor Santa Clara 
calculator. Digit current is in range of 5-50 mA. from either 4.5 V, 6 V, or 9 V.— 'Interface Da- CA, 1978, p 5-52-5-53. 



282 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



/7/ b n n n 
ui O u O 



7227 



CARRY/BORROW — 
ZERO- 



EQUAL— 



4-BIT 
DATA BUS 



COUNT INPUT- 



DATA TRANSFER _ 
(FROM PROCESSOR) 



CONTROL WORD READ. 
(FROM PROCESSOR) 



•HI 




BINARY LINE STATES— Simple circuit using 
four LEDs and one inverter (which may be a 
transistor or spare gate) displays all four pos- 
sible states on two binary lines. When levels of 
lines X and Y are the same, A and B will be off. 
Inverter then places C and D at different levels 
so one LED (C or D) will be on. Reverse situation 
occurs when X and Y are at different levels. — D. 
Straker, Binary State Indicator, Wire/ass World, 
Feb. 1977, p 44. 



DISPLAY 
CONTROL 



- SV 



TIMER DRIVES LED DISPLAY— Intersil 7227 mi- 
croprocessor-controlled timer provides direct 
drive for LED display under supervision of mi- 
croprocessor. Tri-state 4-bit data bus serves to 
read in control word such as up/down, store. 



reset, or load, then deliver counter data, feed in 
settable register word, or preset counter to in- 
itial value. — B. O'Neil, IC Timers — the "Old Re- 
liable" 555 Has Company, EDN Magazine, Sept. 
5, 1977, p 89-93. 

BCD FROM 



KEYBOARD ' 



9 









i_r 



XL 



°,c G « I 



IS 



IS 



> 1 1 fc ^-^^-E-LJ^ 
X 



KEYBOARD 




STROBE 


G, 


= 7400 


G, 


= 7404 


G, 


= 7404 


G, 


= 7400 


G 5 


- 8 = 7475 



- H M>-^-r : P t> 



u 



SEGMENT 
DECODERS 



< G 7 



o — i-p^-^-^-iiy 



IS 



DIGIT SHIFTER FOR DISPLAY— Circuit takes 
BCD output from 10-key keyboard and shifts 
each number, as entered, from right to left on 
display panel. Internal clock is not used. Key- 
board strobe is delayed 2 ms to allow time for 



keyboard switches to stop bouncing. BCD out- 
puts from G 5 -G e go directly to 7- or 10-segment 
decoder driver, such as SN7447 decoders driv- 
ing RCA DR-2100 series low-voltage readouts. 
All resistors are 220 ohms. Capacitors for G, B 



and G 1D are 1000 pF, and capacitors for other 
gates are 240 pF. Article traces circuit opera- 
tion. — T. OToole, Transfer Parallel Information 
Without a Clock, EDN Magazine, Aug. 1, 1972, 
p59. 



DISPLAY CIRCUITS 



283 



O- 



5 - V0LT bcd :0—| 

IN "* 

OH 



LOGIC 
SWINGS 



5 V 

1 



\J U LIQUID 



CMOS DRIVE FOR LCD— Seven-segment liquid 
crystal display digit can be driven directly by 
CD40S4A, CD4055A. or CD40S6A CMOS be- 
cause these circuits contain internal level-shift- 
crystal ing feature needed to convert 5-V input logic 
swings to 30-V peak AC signal required for driv- 
ing dynamic-scattering LCD. — "COS/MOS Inte- 
grated Circuits/' RCA Solid State Division, 
SomervHIe, NJ, 1977, p 629. 



DF OUT 



V SS |"EE 

6 6 

OV -ICV 



r 



4 kHz 
Scan Oscillator 
Cathode Blanking 



1 



VDD 



MC 14022 

Octal 

Counter /Divider 



CE 

VSS Q0Q1 



_L~ 



CE 
Q0 Ql 



1 2 3 4 5 6 7 



MC3490P 
Anode Drivers 



12 3 4 5 6 7 



(1/41MC14011 
P16 




0.001 
P8 



To 
_o System 

Multiplexer 



12 3 4 5 6 7 

Inputs 



Outputs 
12 3 4 5 6 7 



1 2 3 4 5 6 



T 



0.001 JiF 



12-Digit Gas Discharge Display 
Burroughs BR13251 



Decimal Point a 



Decimal Point 



BCD 
nputs ' 



EN V DD a 

RB1 b 

MC 

14558 

A BCD d 



C Segment 
Decoder 
O 



j Control 



56 k J 56 k | 



1 2 3 4 5 6 

Outputs 

MC3491 
Segment Drivers 
Inputs 
12 3 4 5 6 



0.05 /JF 



390 k 
330 K 



Current Prog 



ramming s A ^ 



7S V 

1/2 W 



(810.05MF 200 V 



12-DIGIT GAS-DISCHARGE— Display anodes 
are referenced to ground and cathodes to -180 
V because number of digits in display is greater 
than number of segment drivers. Positive-logic 
CMOS address circuits are powered by -10 V, 
with Motorola MCI 4558 decoder outputs cou- 



pled to MC3491 segment drivers. Scan circuit is 
directly coupled to MC3490P anode drivers. 
Digit scanning is derived from two cascaded 
MC14022 octal counter/dividers. Required 12 se- 
quenced output pulses are achieved by reset- 
ting counters with Q7 output of second counter. 



Counter output also controls system multi- 
plexer (not shown) to give synchronization of 
entire display system. — A. Pshaenich, "Inter- 
face Considerations for Numeric Display Sys- 
tems," Motorola, Phoenix, AZ, 1975, AN-741, p 
23. 



284 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




8-DIGIT LED DRIVE— National DM8863 8-digit 
LED driver is used in conjunction with DM75491 
and DM8861 drivers for driving eight common- 
mode LED digits operating in multiplex mode. 
Circuit also provides logic control for decimal 
point. — C. Carinalli, "Driving 7-Segment LED 
Displays with National Semiconductor Cir- 
cuits," National Semiconductor, Santa Clara, 
CA, 1974, AN-99, p 10. 



18 



TTV 






MOST 

SIGNIFICANT 

DIGIT 

(81 



TO DIGITS 



s 



DIGIT 
121 



T (7) (61 (6) (41 (3) f 

ntHftri 



LEAST 

SIGNIFICANT 

DIGIT 

(II 



16 14 12 10 7 
18 DM8863 

17 15 13 11 8 



•SEGMENT CURRENT LIMIT RESISTORS 
"EITHER SINGLE DIGIT, MULTI -DIGIT. NSN 33, OR EQUIVALENT 



V D0 - 15 V 
V SS - V 



Square 
Wave 

Excitation 



Latch 
Disable 



Control 
Inputs 



a b c d e f g 
Ph MC14543 

BCD 7 Segment 
Latch/Decoder/ 
DriverFor LCD 
LD Bl 

A B C D 



Mi l l 



a b c d e f g 
Ph 



A B C D 



QO Ql Q2 Q3 

(1/2) MC14518 
Dual BCD 
Up Counters 



I 



I I I I I 



a b c d e f g 



LD Bl 

A B C D 



QO Ql Q2 Q3 

En 



(1/2) MC1451S 



I 



M I I I 



b c d e f g 



A B C D 



QO Ql Q2 Q3 



(1/2) MC14518 



QO Q1 Q2 Q3 



(1/2) MC14518 



gized, backplane and segment drive signals BCD inputs are generated from cascaded 

4-DIGIT DIRECT-DRIVE LCD— Each digit of liq- have same phase and magnitude so there is no MC14518 dual BCD up counters.— A. Pshaenich, 

uid crystal display has separate counter, latch, voltage across display. When segment is to be "Interface Considerations for Numeric Display 

decoder, and driver. Excitation signal also feeds energized, signals are 180° out of phase so Systems," Motorola, Phoenix, AZ, 1975, AN- 

LCD backplane. When segment is to be deener- square-wave voltage is twice IC supply value. 741, p 5. 



DISPLAY CIRCUITS 



285 



TWO-INPUT RED/GREEN LED— Uses Monsanto 
MV5491 having red and green LEDs in same 
housing, connected inversely in parallel so cur- 
rent in one direction gives green and reverse 
current gives red. Two different drivers are 
used, SN75452 noninverting and SN75451 in- 
verting. Each LED pair shows one color for cor- 
rect polarity at its driver input and other color 
for opposite polarity. — K. Powell, Novel Indi- 
cator Circuit, Ham Radio, April 1977, p 60-63. 








220 
-^A O+SV 




I00 
* — V\* O + SV 



I00 
— Wv O+SV 




Scan 
Oscillator 
f s «= 3.5 kHz 
220 k 



0.001 MF 



8-DIGfT MULTIPLEXED LED— CMOS multiplex- 
ing technique uses recirculating memory. Eight 
BCD words are parallel-loaded by strobe pulse 
into four MC14021 8-bit static shift registers. By 
feeding output back to input, information is 
continually recirculated within each shift reg- 
ister at clocked 3.5-kHz scan rate. Four serial 
output lines are fed to MC14511 7-segment de- 
coder/driver. 3.5-kHz scan oscillator also clocks 
MC 14022 octal counter/divider whose eight se- 
quential output pulses form digit-select control. 
Common-cathode display is used. — A. Pshaen- 
ich, "Interface Considerations for Numeric Dis- 
play Systems," Motorola, Phoenix, AZ, 1975, 
AN-741, p 15. 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



ZERO SUPPRESSION— Simple CMOS circuit 
using MC14011 quad two-input NAND gate and 
MC14558 IC provides zero suppression for mul- 
tiplexed displays in which scanning is left to 
right for leading-zero suppression and right to 
left for trailing zeros. Article covers operation of 
circuit. — J. J. Roy, Eliminate Excess Zeros in 
Multiplexed Displays, CDN Magazine, Sept. 5, 
1975, p 77. 




BLANKING 



BCD-TO-7 SEGMENT DECODER 



EN 


RBI 


BCD 

INPUT 

CODE 


RBCT 


FUNCTION 
PERFORMED 




1 
1 
1 



1 
1 

X 


X 
X 


1-9 



1 
1 

1 


LAMP TEST 
BLANK SEGMENTS 
DISPLAY ZERO 
BLANK SEGMENTS 
1-9 DISPLAYED 



X = DON'T CARE 
RBI = RIPPLE 

BLANKING 

INPUT 

RBO= RIPPLE 

BLANKING 
OUTPUT 



er 



TIMING FOR ZERO SUPPRESSION CIRCUIT 
NEW BCD DATA TO 14558 INPUTS" 

BLANKI NG (EW 

XSD"* 

RBI 

RBO 

A NO CAPACITOR 

A 100 pF CAPACITOR 

UNBLANK FF.Q 

TIME WHEN 

DISPLAY BLANKED 

"FIRST AND SECOND DIGITS ARE "0" AND THIRD DIGIT IS NONZERO 

IN EXAMPLE TIMING 
•XSD - MSD FOR LEADING ZERO SUPPRESSION 

XSD = LSD FOR TRAILING ZERO SUPPRESSION 



1 M 4-i t-i- 



MC1A511 



LE 

A B C D 



a ■ J 9 a 






■f 



_ 'a a" Tg 

.. 1 ± .. i 



LE 
A B C D 



+ ID 




0.1 MF 

6-DIGIT FLUORESCENT TRIODES— Uses two 
sets of cascaded counters and decoders with 
series switching of positive voltage to anode 
with MC14511 ICs. Digit scanning is accom- 



plished by turning on grid control transistors 
Q1-Q3 with negative-going digit select outputs 
of one MC14553. Timing for counters is derived 
from MC14572 logic elements, with disable 



pulse obtained from two astable MVBRs. Dis- 
play digits can be packaged individually or in 
single envelope. — A. Pshaenich, "Interface Con- 
siderations for Numeric Display Systems," Mo- 
torola, Phoenix, AZ, 1975, AN-741, p 9. 



DISPLAY CIRCUITS 



287 



REG 5V 
QVCC 



■°IST 
LED 
DIGIT 
ANODE 

o2ND 



03 RD 



04TH 




o5TH 



06 TH 



STROBING LEO DISPLAY— Applies power in se- 
quence to segments of display, so fast that eye 
cannot detect flicker, to reduce drain on power 
supply. Input of 1000 Hz can be taken from tim- 
ing chain of circuit that is driving display. 7492 
divide-by-12 counter gives scan frequency of 
83.3 Hz for display- Binary output of 7492 is con- 
verted to 1-in-10 output by 7441 decoder for se- 
quential drive of 2N3904 PNP pass transistor 
that grounds LED which is to be lighted.— W. K. 
McKellips, Strobing Displays Is Cool, 73 Maga- 
zine, Nov./Dec. 1975, p 49-50. 



+ 5V 
6 



g t e <t c b a TO SEGMENT LINES 
10009 9 » 0F ALL 8 LED DISPLAYS 



DIGIT DRIVES TO COMMON CATHODES OF DIGITS O TO 7 
x ? *6 X5 X4 X3 X2 




n 

13 14 15 I 2 3 4 

D D D D D D D 
7 6 5 4 3 2 1 



8 7 6 5 4 



DATA INPUTS FROM PARALLEL OUTPUT PORT 



MULTIPLEXING EIGHT DIGITS— Uses only one 
7-segment driver for eight digits of parallel BCD 
data on eight-LED display that can use MAN 4 
or DL764 7-segment LEDs. Power is supplied to 
only one digit at a time but is switched at high 
enough rate so all digits appear to be on. Uses 
one eight-channel 74151 multiplexer for each of 



the 4 data input bits. Multiplexers and demul- 
tiplexer are addressed by 7493 counter that is 
incremented at about 4 kHz by 555 oscillator. 
IC1 1 is connected for three- to eight-line de- 
multiplexing. IC7-IC10 are peripheral interface 
gates, each sinking up to 300 mA fpr its LED. 
7448 decoder/driver converts BCD data to 7-seg- 



ment code for driving segments of LEDs. For 
74151 and 74155, pin 16 goes to +5 V and pin 8 
to ground. Pin 8 of 75451 goes to +5 V and pin 
4 to ground. Pin 5 of 7493 goes to +5 Vand pin 
10 to ground.— J. Hogenson, Multiplex your 
Digital LED Displays, BYTE, March 1977, p 122- 
126 and 128. 



288 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




-40 
150V 



U50V0C 
LINE 



i 

If- '.:;■ 



T 



IiOOO 
J5Y ,. 



rr — rr 

T I I 4 [ i 



J 



2M; 



TO COMMON 

■c" ° 



in 



T"- F OV LINE T 



I^ 



:h^zd 



i> 



TWO MESSAGES WITH NIXIES— Circuit flashes 
two messages alternately on same Burroughs 
giant Nixie B7971 display. Lighted segments 
needed on individual Nixies to form desired 
wording are divided into three strings. Seg- 
ments A are common to both sets of letters and 
numbers. Segments B are those required with 
A segments to form first message. Segments C 
are those required with A segments to form sec- 
ond message. Changeover from segments B to 
C is done with switching transistors controlled 
by 555 timer and 7476 or 7473 flip-flop. Decimal 
or other punctuation is formed with NE2 neon 
and 100K resistor wired in series between pin 
13 of a Nixie and B or C. Article gives construc- 
tion details. — J. Grimes, Put Your Name in 
Lights, 73 Magazine, Nov. 1976, p 60-61. 




----^ 



5-DIGIT LED REAL TIME— Circuit provides forward current for display is about 40 mA. All quad drivers.— A. Pshaenich, "Interface Consid- 
stroblng of LEDs so peak current and light out- like anode segments of common-cathode dis- erations for Numeric Display Systems," Moto- 
put are greater for same average current. Peak plays are driven by emitter outputs of MC75491 rola. Phoenix, AZ, 1975, AN-741 , p 13. 



DISPLAY CIRCUITS 



289 




PWM BRIGHTNESS CONTROL— Single TTL IC 
combines functions of oscillator and modulator 
to provide intensity control of solid-state dis- 
play by pulse-width modulation. Fan-out of 10 
is available from Q output, suitable for displays 
such as Hewlett-Packard 7300 series, and 
smaller fan-out is available from other Q ter- 
minal.— C. Bartram, P.W.M. Oscillator to Vary 
Display-Intensity, Wireless World, March 1976, 
p89. 



1N41A8 



TO LATCH NO l < 



TO LATCH NO. 2 





t 




■*• (000 Hi IN 


**50K 

2 7K 


l- 


3,4 




74122 




=k 067|»F 


8 TO 7447 

PIN 4 








*> 


2,7 






TO OTHER 
7400 OUTPUTS 

MULTIPLEXING LED DRIVERS— Duty cycle of 
each display digit can be varied from 10% (full 
on with strobing) to less than 1% (almost off). 
Circuit uses 7490 and 7442 as 1-of-10 multiplex 
driver to strobe cathodes of display digits 



through Q1, Q3, etc and turn on required 7400 
multiplex gate through 02, Q4, etc. Outputs of 
7447 are polarity-inverted by QA, QB, etc, which 
can be Sylvania ECG 159 rated at 200 mA. Q1, 



03, etc can be ECG 123 or HEP S0002, while Q2, 
Q4, etc can be any silicon PNP transistor. — B. 
Hart, Current-Saver Counter Display, 73 Maga- 
zine, June 1977, p 174-176. 



290 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




SI-ABBREVIATION DISPLAY— Programmed 
Signetics 8223 256-bit PROM is used as alpha- 
meric display having five 7-segment digits con- 
nected to form alphameric simulation of abbre- 
viations for second, millisecond, microsecond, 
hertz, kilohertz, and megahertz as SEC, SEC-3, 
SEC-6, H2, H2 3, H2 6. Binary counter U3, 4-16 
line decoder, and 5-digit parallel-connected 
Hewlett-Packard display form simple multi- 
plexer that addresses memory U4 one word at 
a time. External 1000-Hz square-wave oscillator 



drives counter and sets scanning rate. Requires 
only one 5-V supply. Article gives truth table for 
memory and circuit for programmer required to 



set it up. — J. W. Springer, Function/Units Indi- 
cator Using LED Displays, Ham Radio, March 
1977, p 58-63. 



Q+5V 



2°— ►- 



2 3 — *- 



2 6 — *- 



2 1 ji. 



2*— *~ 



2 7 — +- 



i 2 — *- 



a 5 — *- 




2x7401 



OCTAL DISPLAY— Cinsuit provides display of 8- built around synchronously operated JK flip- gates and inverters. Oscillator multiplexing fre- 

bit data word in conventional octal form for con- flops provides digit and data selection. The two quency is about 2 kHz.— R. D. Mount, Octal Dis- 

venience in experimentation with microproces- or three bits appropriate to each display are play for Microprocessors, Wireless World, 

sors and smaH computers. Three-state counter steered to 7-segment decoder by wired-AND March 1977, p 41. 



DISPLAY CIRCUITS 



291 




MULTIPLEXED BRIGHTNESS CONTROL— De- 
veloped for use with single-chip digital clocks 
in which several displays are multiplexed. Pro- 
vides automatic brightness control by using 
variable duty cycle and switching it on and off 
in synchronism with display of time. Uses 555 
timer in monostable mode, triggered by multi- 
plex oscillator to determine off time of display. 
When ambient light is bright, resistance of 
ORP12 photocell is low and display is on most 
of time. Set 470K pot to give low light output 
without mistriggering under dark conditions. 
Timer can also drive decimal point directly and 
give matched brightness. — M. G. Martin, Au- 
tomatic Display-Brightness Control, Wireless 
World, April 1976, p 81. 



0i "\ 



TO ~» ♦: < + 5V 

JJ SOURCE 




PENDULUM DISPLAY— Ten series rows of LEDs 
or Christmas-tree lights mounted behind dif- 
fused plastic are energized sequentially left to 
right, then right to left by counter-driven drivers 
to create illusion of swinging pendulum. Circuit 
includes provision for pause at each change of 
direction, as in actual pendulum of clock. Article 
traces operation of circuit in detail. — E. A. Flynn, 
Put a Pendulum in Your Electronic Grandfather 
Clock, EDN Magazine, May S, 1975, p 88 and 90. 



LARGE LAMPS 
- PENDULUM 



292 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




R2-R8 - 330 



LEDs can be Radio Shack 276-1805, and display 
BCD DECODER— Drive for 7-segment common- using RS7404 hex inverter and four LEDs shows is 276-053.— F. M. Mims, "Integrated Circuit 
anode digital display is provided by RS7447 BCD input in binary form for decimal digits 0-9. De- Projects, Vol. 6," Radio Shack, Fort Worth, TX, 
to 7-segment decoder. Binary input indicator veloped for classroom demonstrations. Red 1977, p 42-52. 




_[~|_SEGMENT SELECT V oo ~> 



i 



* 15V 



DISPLAY 
SUPPLY 
-180V 



I 



1N4148^ 



y~ ; 



n n n / / o O O 
/_/. /_/. /_/. /_/. /_/. /_/. /-/. 

GAS-DISCHARGE DISPLAY (BECKMAN SP-300 OR SP-400) 



BRIGHTNESS 
CONTROL 



CATHODE 
DRIVER 

/DIONICS\ 
V Dl 300 / 



£ 



12 



dp 



820k ' 
-vW — i 



MULTIPLEXING 7 DIGITS— Uses Motorola 
MC3490 anode driver for active-high inputs 
(MC3494 for active-low inputs) to accept digit- 
select signals from multiplex logic source and 
drive display anodes directly. Constant cathode 



10 

currents are maintained for gas-discharge dis- 
play by Dionics D1-300 IC, to provide constant 
brightness without using supply-voltage regu- 
lation. For each digit added to display, equal 
number of anode drivers is required. Only one 



•SP-400SERIESONLY 

cathode driver is needed because all cathodes 
are bused together. — D. Sien, Multiplex Display 
Circuit Features Minimum Parts Count, EDN 
Magazine, May 5, 1977, p 1 12. 



DISPLAY CIRCUITS 



293 



NANOSECOND PULSE DETECTOR— Used to 
provide visual indication of presence of a non- 
repetitive digital pulse having microsecond or 
nanosecond width. Bistable IC transfers pulse 
information from its data input to the Q output 
on positive-going edge of clock pulse, to ener- 
gize LED indicator.— P. V. Prior, Digital Pulse 
Detector, Wireless World, March 1976, p 90. 



r^° 



pulse T 

input I 



screened 
cable 





clear 
clock 
preset 




I 




data 


,s> 




' LED 











SN74.76 or 
ec^ui valent 




INDEX NOTCH 



TO CONTROLLED LOGIC- HIGH 
LEVEL WHEN GREEN LED IS ON 



TWO-COLOR LED— Dual LED D2 shows green 
when normally off momentary switch SI is 
moved to START and shows red when moved 
to STOP. Latching circuit using two 7404 TTL 
inverters serves as run and halt flip-flop and also 
debounces switch. Momentary contact at 
START toggles latch, biasing green LED. D1 
shorts R2, leaving R1 to limit forward current to 
about 20 mA for green. R1 and R2 limit current 
for D1 and brighter red LED to about 10 mA for 
momentary contact at STOP. — E. W. Gray, LEDs 
Light Up Your Logic, BYTE, Feb. 1976, p 54-57. 



(1/6) MC14572 



(,/6) MC14572 




5-DIGIT FLUORESCENT DIODES— Real-time nal scanner. Scanning rate is controlled by in- Pshaenich, "Interface Considerations for Nu- 

driveforfive-decadecounterrequiresonlythree verters 4 and 5 of MC14572. Multiplexed BCD meric Display Systems," Motorola, Phoenix, 

ICs. MC14534 contains five-decade ripple outputs go to MC14543 7-segment decoder AZ, 1975, AN-741, p 10. 

counter with output time multiplexed by inter- whose outputs drive fluorescent diodes.— A. 



294 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



/* . M'U t 




BINARY DEMO— Two sections of SN7400 quad 
gate form low-frequency MVBR serving as 
pulse source for SN7490 decade counter. Rate 
is low enough so blinking of LED status indica- 
tors in MVBR can be seen, as indication of pulse 
generation. Similarly, LEDs of counter blink to 
indicate counts of 8, 4, 2, and 1 from left to right, 
with combinations of lights coming on to dis- 
play binary values to 15 before recycling. Ideal 
for Science Fair exhibit. — A. MacLean, How Do 
You Use ICs?, 73 Magazine, Dec. 1977, p 56-59. 



2.7Vdc 



PULSED LED — Circuit can generate peak cur- 
rents above 1 A with pulse widths greater than 
10 ms at repetition rates of 12 kHz with effi- 
ciency better than 90%, for 100-mA current 
drain from 2.5-V battery- Rise time of pulses is 
0.2 ms. Can be used in low-light-level TV sys- 
tems where high peak radiation gives better re- 
solving power than constant illumination hav- 
ing same average power. Also useful for LED 
pilot lamps in battery-operated equipment and 
as low-power strobe for studying mechanical 
motions. — J. Dimitrios, Current-Pulse Genera- 
tor for LED's, EDNIEEE Magazine, July 1, 1971, 
p51. 



CORE: FERROXCUBE 
266CT125 




2N3019 



LED 

MONSANTO ME5-A 




'mi \m2 ?M3 I M4 t M5 T M6 T M7 



MAGNETIC 
REED 
SWITCHES 



LED WIND VANE— Ceramic magnet attached to 
rotor closes magnetic reed switches positioned 
at 45° intervals in circle around rotor. Eight wind 
directions are represented as 0-7 in binary no- 
tation, so = NW, 1 = N, 2 = NE, 3 = E, 4 = SE, 
5 = S, 6 = SW, and 7 = W. Since requires no 
switch, only seven switches are needed in roof- 
top indicator and only four wires need be run to 
binary decoder (wires A, B, C, and ground) driv- 
ing LED rqadout in house. Transistors are 
2N3641, and diodes in matrix used at vane lo- 
cation are 1N914 or 1N4148 silicon. — W. L. 
MacDowell, Digital Wind Direction Indicator, 73 
Magazine, Nov. 1974, p 40-42. 



:^l 



1 ""H"! ' <^i 



:i 



■ "rt*"} ■ "W~i "W"i ■ "W~i 



:^l 



DIODE MATR 



ix-' 



1 "Hri ' "W"| 



:5j 



> 6 6 



P 7 



-FOUR WIRE ROTOR 
CABLE 



DISPLAY CIRCUITS 



295 



(1/4) MC14001 



3'A-DIGIT MULTIPLEXED LCD— Uses MLC401 
field-effect liquid crystal display, which is more 
suitable for multiplexing than dynamic-scatter- 
ing LCD. Counters, latches, multiplexer, and 
scan circuits are all in MC14553 3-digit BCD 
counter whose outputs feed MC14543 decoder 
and driver for display. Excitation frequency of 
100 Hz is derived from square-wave oscillator 
G1-G2 having exactly S0% duty cycle. Scan fre- 
quency is about 500 Hz, giving display refresh 
rate of 170 Hz, which is well beyond detectable 
flicker rate.— A. Pshaenich, 'Interface Consid- 
erations for Numeric Display Systems," Moto- 
rola, Phoenix, AZ, 1975, AN-741, p 6. 



Latch Enable 
Disable 



Master 
Beset 




Motorola 
MLC401 
Field-Effect 
Liquid Crystal 
Display 

LSD 



1/2 Digit 




100-LED SOLID-STATE OSCILLOSCOPE— Flat 
display of LEDs replaces cathode-ray tube of 
oscilloscope. Suitable for classroom demon- 
strations even though resolution is poor. Am- 
plified input signal is fed to upper ends of all ten 
vertical columns of LEDs. Under control of time 
base, scanner completes circuit at bottom of 
each column in turn. Vertical columns are made 
voltage-sensitive by resistors paralleling LEDs. 
Gate circuit using section of 7400 provides trig- 
gering when desired. Voltage-sensitive bar- 
graph readouts formed by vertical columns are 



scanned by 7490 decade counter and 7441 de- 
coder. Sweep rate of display is adjustable from 
1 to 20 vertical columns per second with R5.— 



F. M. Mims, "Electronic Circuitbook 5: LED Proj- 
ects," Howard W. Sams, Indianapolis, IN, 1976, 
p 92-96. 



296 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




INPUT: 



15V 



1.4V<E K <SVr~j 
(0V<E 1 „<1.4VJ L 



LED ON 



LED OFF 



' A, operated from 
+5 to reduce 
power dissipation 



OP AMP DRIVES LED— LM301 A is used as open- 
loop voltage comparator, with LED receiving 
total source current of about 20 mA from 
opamp. Input is TTL-compatible, with R,-R 2 ref- 
erence divider biasing opamp in center of TTL 
output transition region. Circuit realizes full 
open-loop speed of opamp since it is uncom- 
pensated and its internal voltage amplifier 
stages are kept out of saturation by clamping of 
D 2 and by inherent current-limiting action. Re- 
sponse times for toggling LED are in microse- 
cond range. — W. G. Jung, Poor Man's LED 
Driver Is TTL Compatible, EDN Magazine, Feb. 
5, 1973, p 86. 



POSITIVE INPUT GIVES RED— Uses Monsanto 
MV5491 dual LED having red and green light- 
emitting diodes connected Inversely in parallel, 
so current in one direction gives green light and 
reverse current gives red. Circuit uses single 
SN75452 IC driver and one section of SN7404 
hex inverter. High or positive input gives red in- 
dication, while low input gives green. Current- 
limiting resistors R1 and R2 have different val- 
ues because voltage and current specifications 
of parallel LEDs are different. Indicator appears 
to change color as input changes. — K. Powell, 
Novel Indicator Circuit, Ham Radio, April 1977, 
p 60-63. 




Hex Butter/Drivers 



* Inverter Buffer/Di 




5x7 DOT MATRIX— Drive for Dialight 745-0005 
64-character alphameric display generates de- 
sired character in response to pattern of Os and 
1s on input lines A1-A6. Timing of sequential 
scanning operation for seven horizontal rows of 



O? l\. 



Dialight 

745-0005 

Alpha- Numeric 

Display 



matrix is controlled by clock that drives binary 
counter having row-selecting outputs A, B, and 
C. Outputs C1-C5 of ROM correspond to vertical 



rows of dots enabled by 1-out-of-8 decoder.— 
"Readout Displays," Dialight, Brooklyn, NY, 
1978, Catalog SG745, p 24-26. 



DISPLAY CIRCUITS 



297 




(TO BLANKING 
INPUT) 



LED DIMMER— Intech/Function Modules A- 
8402 is used in voltage-to-frequency mode to 
provide controllable dimming of LED display by 
varying frequency of blanking input to display 
driver. Display is pulsed on and off rapidly; the 
higher the duty cycle, the brighter the display. 
At highest input voltage the converter is forced 
out of linear region, making its mono remain on 
continuously for brightest display. — P. Pinter 
and D. Timm, Voltage-to-Frequency Convert- 
ers — IC Versions Perform Accurate Data Con- 
version (and Much More) at Low Cost, EDN 
Magazine, Sept. 5, 1977, p 153-157. 



GIANT-NIXIE SIGN— Simple power supply 
drives any desired number of alphameric Nixie 
characters each 214 inches high to form Illumi- 
nated house numbers, "ON THE AIR" sign for 
amateur station, or "BAR IS CLOSED" sign for 
party room. Connect 3.3K resistor from +150 V 



.5 A 

FUSE. 3 3 o 
O fTlr-'WV- 

120 vnc 



+ I50V 

— • — I 



J6uF 
"?50V 



to pin 13 of each Nixie, and connect to point Y 
(-150 V) each segment to be lighted. Sign can 
be changed at any time by resoldering connec- 



CIMEG <3.3K 




tions to segments. Diode must handle AC line 
voltage.— J. Grimes, Display Yourself in a Big 
Way, 73 Magazine, Nov./Dec. 1975, p 186-188. 



\. 



3 



2 



"^. 



Sa Sb Sc Sri Se Sf Sg dp 
MMS777 
D1D2D3 D4 05 D6 D7 



Vd. 



\. 



dp Sg Sf Se Sd Sc Sb Sa 

. /_/. /_/. /_/. /_/. O. O. NSA " 61 



LV CNDVcc 
IND 



OS8977 




KEYBOARD 



CALCULATOR CHIP 



DISPLAY DRIVER 



6-DIGIT FOUR-FUNCTION— National MM5777 
calculator chip requires only keyboard, 
NSA1161 LED display, DS8977 digit driver, and 
9-V battery to provide add, subtract, multiply, 
and divide functions. Calculator chip includes 



keyboard encoding and key debouncing cir- 
cuits, along with all clock and timing genera- 
tors. LED segments can be driven directly, with- 
out multiplexing. Seventh digit position is used 
for negative sign of 6-digit number and as error 



LED DISPLAY 

indicator. Leading and trailing zero suppression 
is included — "MOS/LSI Databook," National 
Semiconductor, Santa Clara, CA, 1977, p 8-84- 
8-89. 



298 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



IOOOHI 
FROM 
IC4 



« 



A. 



744 2 

IF 



ZNayub 



C I I -J J V o 



2 i- - 

j in 



STROBING LED DISPLAY— Sequential strobing 
of individual LED displays, at rate fast enough 
to eliminate flicker (about 10% duty cycle), cuts 
power requirements of LEDs and eliminates 
need for power-wasting resistors in series with 
digit segments. Circuit uses 7492 binary counter 
connected to divide by 10, continuously clocked 
by 1000-Hz signal from external counter time 
base. Each of the 10 counter states is decoded 
by 7442 decoder for use in turning on PIMP 
switch transistor connected in series with 
anode of each 7-segment LED digit. Digits are 
thus turned on for 10% of time at 100-Hz rate. — 
B. Hart, Current-Saver Counter Display, 73 Mag- 
azine, June 1977, p 174-176. 



POSITIVE INPUT GIVES GREEN— High or posi- 
tive input to circuit gives green indication in 
Monsanto MV5491 dual red/green LED, and low 
input gives red. Circuit uses single SN75452 IC 
driver and one section of SN7404 hex 
inverter. — K. Powell, Novel Indicator Circuit, 
Ham Radio, April 1977, p 60-63. 




CHAPTER 26 

Fiber-Optic Circuits 



Includes LED modulators and photodiode or phototransistor receivers for 
single- or multiple-fiber data links handling audio, data, and teleprinter 
signals. Circuits are also given for infrared receivers and transmitters, high- 
voltage isolator links, laser-diode modulator, Manchester-code demodulator, 
and fiber light-transmission checker. 



+SV 



DATA COUPLER WITH ISOLATION— Length of 
fiber or polystyrene rod determines amount of 
voltage isolation provided between digital or 
analog signal input and Fairchild FPT 100 pho- 
todetector driving Optical Electronics 9720 
opamp having 100-mA output for driving ca- 
bles, relays, or loudspeakers. LEO can be Mon- 
santo MV50 handling up to 200 mA. Output of 
opamp is zero for no light. Pulse-duration mod- 
ulation should be used for transmission of an- 
alog data. — "High Voltage Optically Isolated 
Data Coupler," Optical Electronics, Tucson, AZ, 
Application Tip 10266. 




+5V 
O 



tJ 



FLV104 
($2) 



•M3 



\ 74540 
I ($1.32) 



25 MHz 

— r— 



■C3808 

t$22) 




SHIELDED 
SOX 



24-MEGABIT DATA LINK— High data-rate ca- 
pability for square-wave pulses is achieved by 
increasing complexity of receiver feeding digital 
output to microprocessor from remote tele- 



2N2369 



«T? 



2N2369 
(S3) 



51* 
•VW- 



1N75S 
($2.25) 



750 pF 



O -'5 TO -25V 



r -VW » » * AAt—O J 



0!lF£ 

S.6k 



330 
-VVV*- 



: 220 -/.w ts. 
>^ — |-W*— ^v. 
73» | 7510^- 
-<C j-vVV^- .» 

,„. <22o v.wr«, ,„, 



($3,301 | 
._ I 



OIGITAL 
OUTPUT 

— o 



Ik TO 10k 
(A/v*— - 



i 



ELECTRONICS- $68.03 
CONNECTORS- $4.80 
CABLE-$1/FT 



printer. Preamp design compensates for noise 
over limited frequency range, giving uniform SI 
N ratio to about 20 MHz. With demonstration 
setup, visible-spectrum LED and photodetector 



shown performed acceptably with 40-foot 
cable. — O. E. Marvel and J. C. Freebom, A Little 
Hands-On Experience Illuminates Fiber-Optic 
Links, EDN Magazine, Nov. 5, 1977, p 71-75. 



299 



300 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Data 
Input 




FIBER-OPTIC TRANSMITTER— Will handle NRZ 
data rates to 10 megabits or square waves to S 
MHz. Input is TTL- or CMOS-compatible de- 
pending on circuit selected. Transmitter draws 
only 150 mA from 5-V supply for TTL or from 5- 
15 V supply for CMOS. Choose R1 to give LED 
drive current for proper operation of system. 
For TTL operation, jumpers J1, J2, and J3 are 



Part* List: 
Ul SN74LS04 
U2 MC14049B 
j Q1 MPS363SA 

Dl MFOEIOOdt MF0E200 
AMP Mounting Bushing #227015 

connected as shown. For CMOS operation, re- 
move J1 and transfer J2 and J3 to alternate po- 
sitions for connecting to U2. Choice of LED de- 
pends on system length and desired data rate. 
Power supply can be HP6218A or equivalent. DC 
voltages shown are for TTL interface, with 
upper valuefor LED on at 50 mA and lower value 
for LED off. — "Basic Experimental Fiber Optic 
Systems," Motorola, Phoenix, AZ, 1978. 



rv u 

I 



Rl I 

100K. < Q 1 

2N3904 



<Z& 



<^ LED 1 



T 




* OPT I0NAL 1 51 CURRENT M0N IT0R 



HIGH-CURRENT INFRARED LED PULSER— Cir- 
cu it operates as regenerative amplifier for deliv- 
ering 10-/ns pulses with amplitude of 1.1 A and 
repetition rate of 1.4 kHz to infrared LED. Suit- 
able for infrared beacon in fiber-optic commu- 
nication and optical radar applications. Drain is 
100 mA from 10-V supply. Use gallium arsenide 
LED such as SSL-55C or TIL32 for high-output 
infrared transmitter. Q2 can be changed to ger- 
manium transistor such as 2N1305 to give peak 
current of 2 A at pulse width of 15 its and 750- 
Hz repetition rate. — F. M. Mims, "Electronic Cir- 
cuitbook 5: LED Projects," Howard W. Sams, In- 
dianapolis, IN, 1976, p 33-35. 



1N914 



TRIGGER 
JI 



,"LT 




0.001 nF 



4.2 V 



FIBER-OPTIC 

TRANSMISSION 

LINE 



12.6 V 



A. 



* 



22 mo 



/ 



t 



4.2 V 



FPT130B 



12.6 V 
TR169 



♦r 



(MERCURY, -T 
600 mA-H) I 



0.1 mF 



~il 1N914 



-12.6 V 



THRESHOLD < 1 MI2 

FILM 



BAN0PASS 
FILTER 



10 Mfi 
FILM 




SENSITIVITY 



-wv— 

100 kfi 
FILM 



fZ 



2N5953 



0.001-jiF, 5% 



POLYCARBONATE OR 
POLYSTYRENE 



4.2 V 




S~l 



4.2 V 



ANALOG OUTPUT 

TO BUFFER AND 

SCOPE 




_r~i_ 



TL064: TEXAS INSTRUMENTS QUAD BI-FET AMPLIFIER OR EQUIVALENT 



LIGHT TRANSMISSION CHECKER— Phototran- 
sistor and quad opamp serve as total-energy 
detector of pulsed-light signals propagated 
through fiber-optic cable of communication 
system. Can be used for checking and compar- 



ing condition of long fibers if light intensity of 
source is held constant. Will also detect 
changes in light intensity and changes in pulse 
width . Circuit gives linear response to light lev- 
els from 100 to 10,000 ergs/cm 2 if minimum 



pulse width is at least 10 ins. A 2 acts as RC in- 
tegrator, giving voltage proportional to total 
light energy received. A* provides comparison 
to fixed level. — E. W. Rummel, Low-Level-Light 
Detector Checks Optical Cables Fast, Electron- 
ics, April 27, 1978. p 148 and 150. 



FIBER-OPTIC CIRCUITS 



301 



* 



u. J~ W1N4001 



7T 






Paru List: 

U1 LF357 

U2 MC7S107 or 

MC75108 
U3 SN74LS26 
AMP Mounting Bushing #227015 




FIBER-OPTIC RECEIVER— Uses MF0D100 PIN 
photodiodeas optical detector for handling me- 
gabit data rates. Minimum photocurrent re- 
quired to drive LF357 opamp U1 is 250 nA. Volt- 
age comparator U2 inverts output of U1 and 
provides standard TTL output. For CMOS out- 
put, quad two-input NAND gate U3 is wired into 
circuit, with jumper J1 connected from U3 out- 
put to output terminal of receiver. Adjust R1 to 
give accurate reproduction of 1-MHz square 
wave with 50% duty cycle at receiver output. — 
"Basic Experimental Fiber Optic Systems," Mo- 
torola, Phoenix, AZ, 1978. 



Power Supply: (15 V) HP6116A or equivalent 
(5 V) HP6218A or equivalent 



LASER-DIODE SOURCE— With transistor 
switching circuit shown for RCA SG2007 laser 
diode, pulses as short as 10 ns are possible at 
repetition rates above 100 kHz. Used in optical 
communication system in which fiber bundle or 
single fiber is attached directly to laser pellet.— 
J. T. O'Brien, Laser Diodes Provide High Power 
for High-Speed Communications Systems, 
Electronics, Aug. 5, 1976, p 94-96. 



PULSE 
GENERATOR 



1 



+40 V 



?p O.lpF 



LASER 
DIODE 



5112 | 3.9 n> 



2N5918 2N6 , 05 r— 

] 3.3 n ys 

> o.oimF 1 ^ -X. 

? 3.3 n 

±r- ' e-A/W-e 



6 CAPACITORS 
0.1 uF EACH 



1~ L 
T T 



-O PULSE 
CURRENT 



-° MONITOR 



irr 

'MUNuF 



2N610B 



1N4007 



15K 



=fc.002 



=fc.47 



>4.7K =fe.002 



L14G2 



& 



470K 
-AAV- 



390pf =fc 



22meg 
-A<\V f 



2N5998 



390pf 



100K! 



^ 



2 N 5999 



47 K 
_WV- 



NOTE: 
Output « 4mv/KHz 



-W/v- 

100 



>10meg 



® 



100pf 



>10K 



DHD800 11 



M.7K 




>1K 






€> 



2N5172 



-0+25v. 



-o Output 



390pf 



10 
-VW- 



D13H1 



Lens placed so fiber just 
illuminates phototransistor 
Fiber 

s=i { I . oe 

Phototransistor 



>» (JIIUIUI 





50-kHz FM OPTICAL RECEIVER— Designed for 

pulse-rate modulation system in which trans- center frequency of 50 kHz. L14G2 GE photo of original audio. Based on circuit in "General 

mitter varies pulse rate of modulated light transistor converts modulated optical light to Electric Opto-Electronics Manual."— I. Math, 

beam in optical-fiber cable above and below RF signal for demodulation and reconstruction Math's Notes, CO, July 1977, p 67-68 and 90. 



302 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



1/10/100-KILOBIT FIBER-OPTIC RECEIVER— 
Choice of input device determines operating 
speed of receiver. MC3405 contains two 
opamps and two comparators, permitting use 
as two-channel receiver. Table gives pin con- 
nections for each channel. — "Basic Experimen- 
tal Fiber Optic Systems," Motorola, Phoenix, 
AZ, 1978. 




Node 


Channel 1 


Channel 2 


A 


13 


9 


B 


12 


10 


C 


14 


8 


D 


3 


5 


E 


2 


6 


F 


1 


7 



Ground: Pin 1 1 



33 



Lens is placed so that LED 
just illuminates fiber 

LED 

CK; D41D1 



(D 



.02 

-It- 
led 

GE LED 55C or f ^r DHD805 
equivalent 



2.2/aH 

NOTE: 
Modulating frequency (KHj) • 50-2vi„ ■+ 




o +25v. 



o Input 



2N5172 



50-kHz FM OPTICAL TRANSMITTER— Uses 
pulse-rate modulation system with center fre- 
quency of 50 kHz. Audio fed into transmitter 
varies pulse rate, for driving LED coupled to op- 
tical fiber. Phototransistor at other end of fiber 
receives and demodulates light signal for recon- 
struction of audio. — I. Math, Math's Notes, CQ. 
July 1977, p 67-68 and 90. 



BW 20 MHz 







=LV104 
($2) 


AMP611X 






7440 )0- 


($2.40) 






INPUT ' 














($3.18) 



(33«!) 

10-MEGABIT LINK — Transmitter and receiver 
for fiber-optic data link between teleprinter and 
microprocessor utilize wide bandwidth of cable 



6 

-15 TO 
-25V 



ELECTRONICS-S30.81 

CONNECTORS-S4.80 

CABLE-$1/FT 



for transmitting data at 10-megabit rate. Re- 
ceiver input requires C3808 PIN photodiode. — 
O. E. Marvel and J. C. Freeborn, A Little Hands- 



On Experience Illuminates Fiber-Optic Links, 
EDN Magazine, Nov. 5, 1977, p 71-75. 



FIBER-OPTIC CIRCUITS 



303 



MANCHESTER' 
ENCODED I 
DATA f. 



TRANSITION 
MARKER 



u 



FF1 




5410102 



V.10102. 




5410104 



% 101 02* 



9528 



RESET 



14 101 02 
| j '/.10104 

•SELECT 




{♦SHIFT 
CLOCK 



STROBE! 



V.10104 

.__" J 

DELAY 



95HO0 
HP 



OV cc 5VDC 




T^L Output 



1-GHz MANCHESTER DECODER— Use of ECL 
flip-flop with toggle rates above 1 GHz makes 
decoding of bit rates approaching gigabit 
speeds feasible. Article gives step-by-step de- 
sign procedure for 48-Mb telemetry application 
using PCM over single optical-fiber cable. — B. 
R. Jarrett, Could You Design a High-Speed Man- 
chester-Code Demodulator?, EDN Magazine, 
Aug. 20, 1974, p 75-80. 



20-KILOBIT FIBER-OPTIC RECEIVER— Photo- 
transistor driving three-transistor amplifier pro- 
vides TTL output for data rates up to 20 kilo- 
bits. — "Basic Experimental Fiber Optic Sys- 
tems," Motorola, Phoenix, AZ, 1978. 



15 Vdc 



15 Vdc 



IR DETECTOR— Photodiode transforms light- 
signal output of fiber-optic cable to electric sig- 
nal. Spectral response of detector closely 
matches that of IR-emitting diode at other end 
of cable, for maximum system efficiency. Rise 
and fall times of detector can be less than 35 ns 
when properly biased and loaded by receiver 
circuit. Developed by Augat, Inc., Attleboro, 
MA, as part of fiber-optic evaluation kit for TTL 
applications.— Fiber-Optic Kit Allows Engineer- 
ing Evaluation of Complete Interconnection 
System, Computer Design, Nov. 1977, p 27 and 
30. 



DETECTOR 
ASSEMBLY 




PHOTO- 
DIODE 



15k, 1% MF 

— vw 



*\(r 



^3£ 

0.1 uF " 



15k. 1% MF 



-de- 



15 Vdc 




-12 Vdc 

HA-262S-5 
OP AMPS 
(HARRIS) 



ADJUST FOR 
OUTPUT SYMMETRY 



NE529 

COMPARATOR 

(SIQNETICS) 



MANCHESTER CODE 
> 



y4CELL 
PURE DELAY 



95HO0 







. 10104 



MANCHESTER-CODE DEMODULATOR— Digi- 
tal approach using ECL provides maximum 
speed, is self-synchronizing for alternate bit- 
pairs, and has minimum complexity. Developed 
for optically coupled 25-channel PCM telemetry 



system used over single optical-fiber channel. 
Undesired transitions in input data are masked 
by creating strobe. Approach recognizes dis- 
tinction between identical sequences that 
would give some output except for time-of-oc- 



currence restriction. Article gives step-by-step 
design procedure, waveforms, and excitation 
table.— B. R. Jarrett, Could You Design a High- 
Speed Manchester-Code Demodulator?, EDN 
Magazine, Aug. 20, 1974, p 75-80. 



304 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



1-MHz LED PULSE MODULATION— Circuit pro- 
vides required low driving-point impedance for 
fast turn-on of gallium arsenide phosphide LED 
used as source for high-speed pulse modulation 
of fiber-optic or otherlight beam. Q, supplies DC 
level and modulation information to emitter- 
follower output stage Q 3 . Output current is 
sensed and limited to about 30 mA by Q?. Turn- 
on time for full brightness is 12 ns. — G. 
Schmidt. LED Modulator, EDNIEEE Magazine, 
June 15, 1971, p 57. 



+ I2V 

03 
2N5I38 



o- 



!39k 



15 



LED 
MV-50 



CR1 
-W- 



Ge 



€> 



Q 2 
2N5I35 



INPUT 
(0.1 VOLT) 
9 



UxlOuF 



2N5138 



270 



122 k 

Ik 
I BIAS 
LEVEL 

^3.3k 




TTY LINK FOR MICROPROCESSOR— Demon- 
stration circuit illustrates use of fiber-optic 
cable with low-cost components for relatively 
narrow-band application, to provide feed from 
remote teleprinter to microprocessor. — O. E. 
Marvel and J. C. Freeborn, A Little Hands-On 
Experience Illuminates Fiber-Optic Links, EON 
Magazine, Nov. 5, 1977, p 71-75. 



CHAPTER 27 

Filter Circuits — Active 



Includes low-pass, high-pass, bandpass, notch, state-variable (2 to 4 
functions), tracking, and equalizing filters covering from 1 Hz to limits of 
audio spectrum, along with gyrator, Q multiplier and variable-Q circuits, 
crossover networks for loudspeakers, and RF circuits providing frequency 
emphasis. 



I 100k I 

* Wi 1 i 




* non-polarized polycarbonate 

TRACKING LINE-FREQUENCY FILTER— Im- 
provements in commutating RC network filter 
extend dynamic range without sacrificing sig- 
nal bandwidth, for reducing interference at fun- 
damental of power-line frequency and harmon- 
ics up to fifth. Although values in circuit are for 



British SO-Hz mains frequency, circuit can read- 
ily be adapted for 60-Hz rejection. Operation in- 
volves commutating 16 capacitors electroni- 
cally at 16 times line frequency. Article gives 
one method of doing this, by driving two 8-way 
multiplexers alternately. Each multiplexer has 



eight MOSFETs, each switched on in turn by 
consecutive input clock pulses. Circuit details, 
design equations, and performance graphs are 
given. Three-position switch gives choice of fil- 
ter characteristics. — K. F. Knott and L. Un- 
sworn, Mains Rejection Tracking Filter, Wire- 
less World, Oct. 1974, p 375-379. 



305 



306 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



10-kHz VARIABLE-Q — Second-order state-vari- 
able filter having center frequency of 10 kHz 
uses all four sections of OP-1 1FY quad opamp. 
Center frequency can be tuned by varying 1.6K 
feedback resistors or by changing 0.01-jtF feed- 
back capacitors. Value of feedback resistor for 
opamp D determines Q of filter, for adjusting 
circuit bandwidth or damping. For higher-fre- 
quency operation, use high-speed opamps such 
as OP-15 or OP-16. — D. Van Dalsen, Need an 
Active Filter? Try These Design Aids, EON Mag- 
azine, Nov. 5, 1978, p 105-110. 



O «/W^ 




NOTES 

A.B.CD- '/« OP-11FY 

CAPACITOR = 10% POLYSTYRE 




15-3500 Hz BANDPASS— Five-pole telecom- 
munication filter using eight Precision Mono- 
lithics OP-08 opamps provides better than 30- 
dB attenuation in stop band. Total supply drain 



is only 4.8 mA for ±15 V supply. — "Precision 
Low Input Current Op Amp," Precision Mono- 
lithics, Santa Clara, CA, 1978, OP-08, p 6. 



FILTER CIRCUITS — ACTIVE 



307 



10-20 kHz BANDPASS— Two CD4047A low- 
pass filters, one connected for 10-kHz cutoff and 
other for 20-kHz cutoff, drive CD4013A flip-flop. 
If output of filter 2 is delayed by C, flip-flop 
clocks high only when input pulse frequency 
exceeds 10-kHz cutoff of filter 2. Waveforms 
show performance when input signal is swept 
through passband.— "CQS/MOS Integrated Cir- 
cuits," RCA Solid State Division, Somerville, N J, 
1977, p 619. 



1„ 



-t-|*TR 
I— RET 



FILTER I 
C04047 



a+TR 
RET 



FILTER 2 
CD4047 



^o 



"OUT 

— O 



iC'lOOpF 



ir 



v, N JonnjiorinRiijuiiiJiiiiir^^ 
oi JUT-n-nju uiMJUinn n-JLJuiJL 
"Jirmnnnj Tinnnr 



C040I3 0. 
Q" 



v OUT. 



JTJUUUL 












1 49.9K 

1 LVvVH 


if 


WV — 

49.9K 




1 49.9K 




> 


i— O ! 


1 24.9KS 


+S^ BAND 

"^ REJECT 


L 


(OPTIONAL) 1 



NOTES: 1. MAKE R1C1 -R2C2 



2.fc = 



_1_ 



2/7RiCl 

■*0*B8) 



1-kHz STATE-VARIABLE WITH Q OF 10— Use of 
all four sections of Harris HA-4602/4605 quad 
opamp gives four types of 1-kHz second-order 
filtering simultaneously. Pot adjustments per- 
mit matching of various RC products allowing 
for noninteractive adjustment of Q and center 
frequency. — "Linear & Data Acquisition Prod- 
ucts," Harris Semiconductor, Melbourne, FL, 
Vol. 1, 1977, p 2-84. 



2 POLE FILTER 



5-kHz SERIES-SWITCHED BANDPASS— N-path 
filter having N of 4, Q of 500, and voltage gain 
of 2 uses DG509 four-channel CMOS differential 
multiplexer having necessary pairs of analog 
switches and decode logic. Dual D flip-flop gen- 
erates 2-bit binary sequence from 20-kHz clock 
signal. Bandwidth is about 10 Hz for 3 dB down, 
centered on 5 kHz.— "Analog Switches and 
Their Applications," Siliconix, Santa Clara, CA, 
1976, p 5-15-5-17. 




LOW PASS FILTER 



BANDPASS FILTER 



:0kHz = l N CLOCK 
. .CLOCK 







DECODE \ 
INTERFACE 


DC 501 












An 


A l 


I 










I 








I 










D 
C 








I 


D O 




























U 







N-PATH FILTER 



308 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



6.8 kA 




700-Hz STATE-VARIABLE— Provides voltage 
gain at center frequency of 1 00 (40 dB) and Q of 
50. Used when simultaneous low-pass, high- 
pass, and bandpass output responses are re- 
quired. Cutoff frequency of low-pass and high- 
pass responses is equal to center frequency of 
bandpass response. Opamps can be 741. Based 
on use of 5% resistors. — H. M. Berlin, "Design 
of Active Filters, with Experiments," Howard W. 
Sams, Indianapolis, IN, 1977, p 184-187. 



3.3 kft 



1.5-kHz NOTCH— Unity-gain state-variable fil- 
ter consists of low-pass and high-pass sections 
combined with two-input summing amplifier to 
give notch response for suppression of 1.5-kHz 
signals. Opamps can be 741. — H. M. Berlin, 
"Design of Active Filters, with Experiments," 
Howard W. Sams, Indianapolis, IN, 1977, p 186- 
189. 



3.3 k& 
v |0 'VW 



3.3 it a 




rt^~* V ' 



"NOTCH 




10-kH GYRATOR— Active filter circuit uses two 
sections of CA3060 three-opamp array as gyra- 
tor that makes 3-/*F capacitor function as float- 
ing 10-kilohenry inductor across terminals A 
and B. Q of inductor is 13. 100K pot tunes in- 
ductor by changing gyration resistance. — "Lin- 
ear Integrated Circuits and MOS/FET's," RCA 
Solid State Division, Somerville, NJ, 1977, p 
152. 



ALL RESISTANCE VALUES ARE IN OHMS 



FILTER CIRCUITS — ACTIVE 



309 



.22 /xF 



60-Hz NOTCH FILTER— Design is based oil pass- 
band gain of 3 and Q of 6. Resistors can be 5%. 
Opamps can be 741 . Notch response is obtained 
by subtracting output signal of bandpass filter 
from its input signal with R 6 . — H. M. Berlin, 
"Design of Active Filters, with Experiments," 
Howard W. Sams, Indianapolis, IN, 1977, p 155. 




2% components us*d 
whon postiblo 



XWpuk 

powor 
amplifier 



THREE-LOUDSPEAKER CROSSOVERS— Active sired level and gives choice of slopes in any part BCY70, BCY71, BCY72, or 2N3906. Article also 

filter network splits AF input into three fre- of frequency band. Article gives design equa- gives circuit of suitable 30-W amplifier.— D. C. 

quency bands each feeding separate 30-W tions and construction details. NPN transistors Read, Active Filter Crossover Networks, Win- 

power amplifier. Design allows adjustment of can be BC107 or 2N3904; PNP transistors can be less World, Dec. 1973, p 574-576. 
any part of frequency characteristic to any de- 



310 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



O *W jf- 



16k 



Hf- 



VF 



ML747 



16k ■ 



<fc 



"4>1 



16k 



.16k 



: vf 



-L7 



10-Hz HIGH-PASS— Equiterminated Butter- 
worth high-pass ladder filter has corner fre- 
quency of 10 Hz and output impedance level of 
16K. Opamps are matched pair in single ML747 
package. Article covers design procedure based 
on use of generalized impedance converters 
and gives frequency response curve. — L. T. Bur- 
ton and D. Treleaven, Active Filter Design Using 
Generalized Impedance Converters, EDN Mag- 
azine, Feb. 5, 1973, p 68-75. 



10-kHz VOLTAGE-TUNED— High-Q circuit 
using Optical Electronics 9831 opamp has sharp 
resonance, as required for analysis of spectrum 
of incoming signal. Reverse-biased silicon junc- 
tions serve as voltage variable capacitors for 
sweeping center frequency over 3:1 range. Val- 
ues shown for three resistors in twin-T network 
give center frequency of 10 kHz. — "Voltage 
Tuned High-Q Filter," Optical Electronics, Tuc- 
son, AZ, Application Tip 10207. 



S i gna l 
Input , 



100k 



1M 
-AAA*. 



MV MV 
1nf 2109 2109 lnf 

1h 




10k 



_L 1nf ^= 1M 
— — • — *^a* — ' 

=±= MV2113 



3.6M 
— vw- 



X 



3.6M 




Sweep 
Input 



-O Output 



■Hh 




R 





"i 



ACTIVE CW FILTER— Modifications made on 
MFJ Enterprises CWF-2 active audio filter per- 
mit maximum flexibility. Circuit provides fixed 
bandwidth of 180 or 1 10 Hz centered on 750 Hz, 
or optional variable bandwidth for which center 
frequency can be adjusted In range of 280 to 
1590 Hz.— H. M. Berlin, Increased Flexibility for 
the MFJ Enterprises CW Filters, Ham Radio, 
Dec. 1976, p 58-60. 



FILTER CIRCUITS — ACTIVE 



311 




< I O OUTPUT 



TWO-STAGE CW— Uses diode threshold detec- 
tor between stages to prevent weak undesired 
signals from passing through until CW signal of 
desired frequency is present, so as to provide 
quiet tuning between signals. Bandwidth of fil- 



ter is sharp (16 Hz), and keyed waveform is 
good. Gain is near unity, and frequency and Q 
are both fixed. — A. F. Stabler, An Experimental 
Comparison of CW Audio Filters, 73 Magazine, 
July 1973, p 65-70. 



INPUT 2.7 K 

o — vw 




VARIABLE Q FOR CW— Fixed-frequency active 
filter gives slowly rising and falling keyed wave- 
form with good slope considering narrowness 
of bandwidth, which is 75 Hz at 3 dB down. Ad- 
justing Q with 1K pot changes bandwidth. — A. 
F. Stahler, An Experimental Comparison of CW 
Audio Filters, 73 Magazine, July 1973, p 65-70. 



-20 V 



.05 



o-jf-^AAr 




NARROW BANDPASS FOR SPEECH— Simple 
audio filter provides about 20-dB gain at band- 
width of 80 Hz. Bandwidth can be narrowed to 
limits of unintelligibility by adjusting 10K pot. 



Input is plugged into phone jack of receiver, and 
headphones are connected to output. Transis- 
tors are SK3004 or equivalent. — Circuits, 73 
Magazine, Jan. 1974, p 125. 



r 



R1 R2 

10 MO 10 MA 
INPUT > WS • VW 



?5M(J 



t-!« 



i_r i 



SN72310 I 

^1 



R1 - R2 - 2R3 

C3 
C1 - C2 - — 



60-Hz ADJUSTABLE-Q NOTCH— Connection 
shown for two SN72310 voltage-follower 
opamps provides attenuation of 60-Hz power- 
line frequency. Setting of R4 determines Q of 
filter. — "The Linear and Interface Circuits Data 
Book for Design Engineers," Texas Instruments, 
Dallas, TX, 1973, p 4-39. 



LE VEL SET 

(SEE TEXT! 

IIMI 



FILTER FEEDBACK 



DETECTED , 
AUDIO O— ^ 
INPUT 




LOW PASS 
FILTERED 
AUDIO OUTPUT 



YPICAL PC 
TERMINATION 
POINT 



ACTIVE AF FOR SSB AND CW— Uses Kinetic 
Technology FX-60 IC (culled from FS-60, FS-65, 
and FS-61 production by manufacturer) as 2.5- 
kHz tunable detected-audio low-pass filter for 
SSB. Provides inexpensive hybrid active filter 
using multiloop negative feedback for low-pass 
transfer functions. External resistors tune filter 



frequency and give choice of Q. High-imped- 
ance buffer Q1 provides nominal gain while iso- 
lating filter from previous receiver stages. 
Opamp U2 boosts overall gain. — M. A. Chap- 
man, Audio Filters for Improving SSB and CW 
Reception, Ham Radio, Nov. 1976, p 18-23. 



INPUT 1£ 

0.02 lift 



110 kn 
— vw — 



r 



.neU^lf' 



110 kn < 



100-Hz HIGH-PASS— Metallized polycarbonate 
capacitors are required for good temperature 
stability in high-pass active filter using voltage- 
follower opamp. Cutoff frequency is 100 Hz. — 
"The Linear and Interface Circuits Data Book for 
Design Engineers," Texas Instruments, Dallas, 
TX, 1973, p 4-39. 



312 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



transistor array 
CA3096 



1 j? 12| ]15 ' 



. 5 Pa ^ext. voltage 

control 



FREQ. CONTROL 
10k lin. 




CONTROLLABLE 12 dB PER OCTAVE ROLL- 
OFF — Frequency at which rolloff starts can be 
set in range between 15 and 15,000 Hz by ex- 
ternal voltage or current. If only manual control 
of frequency is required, short points X and Y 
and connect them to wiper of 10,000-ohm log- 
arithmic potentiometer that is positioned be- 
tween -12 V and ground. — T. Orr, Voltage/Cur- 
rent Controlled Filter, Wireless World, Nov. 
1976, p 63. 



-12V 



O e 2 = 10cos2<ift q e, =10sin27ift 




QUADRATURE OSCILLATOR— Addition of quadrature oscillator.— Y. J. Wong, Design a Oscillator, EON Magazine, Sept. 20, 1978, p 
diode limiter and positive-feedback resistor to Low Cost, Low-Distortion, Precision Sine-Wave 107-1 13. 
UAF41 universal active filter gives precision 



FILTER CIRCUITS — ACTIVE 



313 



10k 



P^ 620n 



0.33uF 




13.2k 



480-kHz LOW-PASS— Butterworth low-pass ac- 
tive filter uses pair of dual opamps with external 
resistors and capacitors to give corner fre- 
quency of 480 kHz and output impedance level 
of IK. Article presents design procedure in de- 
tail and gives frequency response curve. — L T. 
Burton and 0. Treleaven, Active Filter Design 
Using Generalized Impedance Converters, EDN 
Magazine, Feb. 5, 1973, p 68-75. 



(a) 



300-3000 Hz WIDEBAND— Used in voice com- 
munication systems where signals below 300 
Hz and above 3000 Hz must be rejected. Second- 
order Butterworth stopband responses are 
achieved by combining low-pass and high-pass 
sections of equal-component voltage-con- 
trolled voltage-source filters. Overall passband 
gain is 8 dB. Opamps can be 741.— H. M. Berlin. 
"Design of Active Filters, with Experiments," 
Howard W. Sams, Indianapolis, IN, 1977, p 148- 
151. 




2ND ORDER 
HIGH-PASS SECTION- 
(300 HZ) 



27kfl 



47 k& 



END ORDER 
LOW -PASS SECTION 
(3,000 HZ) 



970 pF 



Hfr- 



0.033/- F 4.15nF 

H( — T-K- 



2.94k 
O-i-vW- 



23.4k 




1.01k 
■VW- 



1> 



!3.03nF 1 R _ 
13.2k 



34.1k 
-^W • 



0.032/jF 



18 dB PER OCTAVE EMPHASIS— Circuit shown 
is result of design procedure given in article for 
active filter that provides frequency emphasis 
at rate of 18 dB per octave between 5 and 15 
kHz. Emphasis does not exceed 40 dB at 20 kHz. 
Design equations include parameters for 
closed-loop gain of opamp. Scale factor is ap- 
plied to input and feedback networks individ- 
ually after design, to give reasonable compo- 
nent values.— B. Brandstedt, Tailor the 
Response of Your Active Filters, EDN Magazine, 
March 5, 1973, p 68-72. 



314 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



> R3 
?1.5K ' * 



R3S50K 



CI 
.001 



IC1 
RS566 



C2i.4?Mf 



C3 



R4 
I — vw- 

100K 



C4 

-II- 



.02pF . 01 (jF 




1 -=-9V 



XTAL 
PHONE 



R5 
100K 



R6 
100K 



TRIANGLE WAVE 
OSC ILLATOR 



ACTIVE FILTER 



■r-'T- 

t ♦ 

PIN 4 PIN 7 



150-Hz HIGH-PASS— Circuit includes variable 
high-frequency source supplying triangle-wave 
input to filter for demonstrating high-pass ac- 
tion. If long supply leads cause oscillation, con- 
nect 0.1-juF capacitors between ground and 
supply pins 4 and 7 as shown. — F. M. Minis, 
"Integrated Circuit Projects, Vol. 4," Radio 
Shack, Fort Worth, TX, 1977, 2nd Ed., p 87-94. 



750-Hz SIXTH-ORDER BANDPASS— Provides 
passband gain of 6 (15.6 dB) and Q of 8.53 by 
cascading three identical second-order filter 
sections. Each section uses multiple 
feedback. — H. M. Berlin, "Design of Active Fil- 
ters, with Experiments," Howard W. Sams, In- 
dianapolis, IN, 1977, p 147-148. 



,033/tF 



.033 /if 




«V„ 



Q INPUT 




2-20 kHz SELF-TUNING BANDPASS— Center 
frequency of filter is automatically adjusted to 
track signal frequency, for optimum noise rejec- 
tion when input frequency varies over wide 
range as it does with many types of vibrating 
transducers. Requires no reference frequency 
and no internal oscillator or synchronizing cir- 
cuits. Frequency range can be extended in de- 
cade steps by capacitor switching. When filter 
is not tuned to input frequency, phase shift is 
not 180° and phase detector applies error signal 
to gate of FET to control its drain-source resis- 
tance. Phase detector A I -A 5 -CR 2 -CR 3 and FET 
form part of negative-feedback loop around fil- 
ter, so error in phase changes resistance of FET 
and thereby retunes filter. Article gives design 
equations, operational details, and waveforms 
at various points in circuit. — G. J. Deboo and R. 
C. Hedlund, Automatically Tuned Filter Uses IC 
Operational Amplifiers, EDNIEEE Magazine, 
Feb. 1.1972, p 38-41. 



J_ COMPARATOR 



DIFFERENTIATOR , 



FILTER CIRCUITS — ACTIVE 



315 




3-kHz NOTCH— Uses three sections of National 
LM324 quad opamp to provide fixed center fre- 
quency of 3 kHz for notch. Single supply can be 
5-25 V. — P. A. Lovelock, Discrete Operational 
Amplifier Active Filters, Ham Radio, Feb. 1978, 
p 70-73. 



m 



STATE-VARIABLE DESIGN— Universal filter 
network using three opamps can provide low- 
pass, high-pass, or bandpass audio response for 
CWand SSB reception. Filter uses onesumming 
block U1, two identical integrators, U2 and U3, 
and one damping network. Cutoff frequencies 
are same as center frequency for bandpass re- 
sponse. Article gives design equations and 
graph for choosing values to give optimum per- 
formance for type of response desired. For 
unity-gain second-order Butterworth filter with 
low-pass or high-pass cutoff of 700 Hz, R is 6800 
ohms and C is 0.033 fiF. Q must be fixed at 0.707 
and R A must equal 1.12 x R„. Thus, if R„ is 2700 
ohms, R„ should be 3000.— H. M. Berlin, The 
State-Variable Filter, QST, April 1978, p 14-16. 




X" 



• 12V 



Signal 
input 

O — 



1 



o — 

vco 

OUTPUT 



SK 

♦— VvV- 



T cb:= 



n — i 

6 <T~**J 



-VA — i 




14 13 12 l 



DISCRIMINATOR 
OUTPUT 



I 



: 300 hf 



3:1 TRACKING FILTER— Connection shown for 
Exar XR-215 PLL IC tracks input signal over 3:1 
frequency range centered on free-running fre- 
quency of VCO. Tracking range is maximum 
when pin 10 is open. R„ is typically between 1K 
and 4K. C, is between 30 and 300 times C where 
timing capacitor C depends on center fre- 
quency. System can also be operated as linear 
discriminator or analog frequency meter cov- 
ering same 3:1 change of input frequency. R F 
can be 36K.— "Phase-Locked Loop Data Book," 
Exar Integrated Systems, Sunnyvale, CA, 1978, 
p 21-28. 



C c COUPLING CAPACITOR* 
C 8 BYPASS CAPACITOR 



316 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




vino— ■*vW-<^ 



1-kHz THREE-FUNCTION— Three-function 

fixed-frequency active filter uses three sections 
of RCA CA3401E, Motorola MC3301P, or Na- 
tional LM3900N quad opamp. Circuit uses high- 



m 



value series resistors for noninverting inputs to 
limit bias current to between 10 and 100 j*A. — 
P. A. Lovelock, Discrete Operational Amplifier 
Active Filters, Ham Radio, Feb. 1978, p 70-73. 




*-O v o 



20-kHz BANDPASS— Provides bandwidth of 
2000 Hz and midband gain of 1 for applications 
requiring narrow-bandwidth bandpass active 
filter. Design procedure is given. — "Audio 
Handbook," National Semiconductor, Santa 
Clara, CA, 1977, p 2-52-2-53. 




10 meg 



P 



016 
3140^ 




' .016 



10 meg 




— ' 3140" 



-Wr 

10K 



-WV- 

10K 



Bout 
HIGH PASS 



e ul 
LOW PASS 



eout 
BANDPASS 




3140 



10K 



NOTCH 



1-Hz STATE-VARIABLE FILTER — Universal filter off, replace 10-megohm resistors with 10K. — D. 

has simultaneous low-pass, bandpass, high- Lancaster, "CMOS Cookbook," Howard W. 

pass, and notch outputs all with cutoff fre- Sams, Indianapolis, IN, 1977, p 343-344. 
quency of 1 Hz. To scale circuit up to 1-kHz cut- 



FILTER 
OUT 
€> 



INPUT O VAr 

10K 
2Q 




O0UT 



GAIN--2Q 2 



1-kHz MULTIPLE-FEEDBACK BANDPASS— Sin- 
gle 741 or equivalent opamp is suitable for ap- 
plications where bandwidth is less than 100%. 
Gain is fixed at -2Q 2 , where Q is reciprocal of 
damping d and ranges from less than 1 to above 
100. Q is changed by varying ratio of input and 
feedback resistors while keeping their product 
constant. For Q of 3, feedback resistor should be 
36 times value of input resistor. — D. Lancaster, 
"Active-Filter Cookbook," Howard W. Sams, In- 
dianapolis, IN, 1975, p 150-154. 




FREQUENCY-TRACKING BANDPASS— High-Q 
active bandpass filter automatically tracks 
input signal frequency over 10:1 range in pres- 
ence of noise. When signal goes outside track- 
ing range, circuit sweeps between low- and 
high-frequency limits until suitable signal reap- 
pears. Circuit is basically voltage-controlled 
bandpass filter using Optical Electronics 3704 



active filter with 5898 analog multipliers. 9813 
opamp connected as Schmitt trigger is main 
element of scanning circuit. Frequency range is 
160 to 1600 Hz, and FM bandwidth of error-volt- 
age output is 20 Hz. — "Frequency Tracking Ac- 
tive Filter," Optical Electronics, Tucson, AZ, Ap- 
plication Tip 10270. 



50-Hz WIEN-BRIDGE NOTCH FILTER— Uses 
opamp in circuit having essentially zero output 
impedance, making additional buffer amplifier 
unnecessary. Article gives design theory and 
covers many other types of notch filters. — Y. 
Nezer, Active Notch Filters, Wireless World, 
July 1975, p 307-311. 



FILTER CIRCUITS —ACTIVE 



317 



LO PASS 
C OUTPUT 
(DC) 



INPUT 




DC LEVEL SHIFTER FOR AF— Circuit using Op- 
tical Electronics 9803 opamps separates AF 
input signal into two outputs. Low-pass output 
contains DC to 10 Hz, and high-pass output has 
frequency content above 10 Hz to upper fre- 
quency limit approaching 10 MHz for opamp 
used. Dynamic output impedance of both out- 
puts is less than 1 ohm. Both outputs have DC 
continuity. DC output of high-pass terminal is 
equal to offset voltage of integrator. DC output 
of low-pass terminal equals DC input plus offset 
voltages of both opamps.— "Automatic DC 
Level Shifter," Optical Electronics, Tucson, AZ, 
Application Tip 10226. 



10k 



VOLTAGE-CONTROLLED BANDPASS— Two 
Optical Electronics 5898 four-quadrant analog 
multipliers and 3704 state-variable active filter 
permit use of voltage control for changing filter 
characteristics remotely without having noise 
pickup problems on control lines. Analog mul- 
tipliers serve as variable-gain blocks that 
change current levels in resistors and in effect 
change resistor values. Circuit has linear rela- 
tionship of frequency to control voltage, con- 
stant gain and Q with frequency, and good tem- 
perature stability.— "Voltage-Controlled Active 
Bandpass Filter," Optical Electronics, Tucson, 
AZ, Application Tip 10269. 



o- 

INPUT 



10k 

-VSA^- 



17 12 



11 



3704 



15 



V-C0NTR0L 
to +10V 
O 




100k 



OUTPUT 



-O 




f c =(160V c )Hz 

Q=lf0 PR0X. 
GAIN =1 



100k 



j">v 9- 
2mA^ 




PASS/REJECT TUNABLE NOTCH— Full rotation 
of ganged tuning control R4 tunes circuit from 
100 Hz to 10 kHz, with position of switch SI de- 
termining whether circuit passes or rejects fre- 
quency to which it is tuned. Maximum selectiv- 
ity, corresponding to maximum height of pass 
curve or depth of reject curve and minimum 
width of either curve, is obtained when R9 is set 
for maximum gain in FET Q4. If R9 is advanced 
far enough with switch set to pass, circuit will 
oscil late and give sine-wave output at tuned f re- 
quency.— R. P. Turner, "FBT Circuits," Howard 
W. Sams, Indianapolis, IN, 1977, 2nd Ed., p 71- 
73. 



318 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



e,(s)CH> 




e in O- 



C«,l«l 



*1 


Cx 


Q 


'neieh 


NOTCH 
DEPTH 


75 kO 


0.001 «F 


9.8 


4.22 kHz 


62 dB 


150 k» 


660 pF 


18.4 


4.22 kHz 


62.7 dB 


220 kfi 


360 pF 


25.0 


4.22 kHz 


62 dB 



4.22-kHz NOTCH— Circuit consists of positive 
unity-gain opamp, RC twin-T network, and T 



network R,C, that determines circuit Q. Variable 
Q feature is controlled by single passive RC net- 
work. Center frequency of notch filter is about 
4.22 kHz. Table gives values of R, and C, for 
three different values of Q.— H. T. Russell, 
Notch Fitter Has Passive Q Control, EDNIEEE 
Magazine, July 1, 1971, p 43 and 45. 



12 dB/octeve ultimate slope 




10-Hz HIGH-PASS UNITY-GAIN— Low cutoff 
frequency is 10 Hz in active filter using opamp 
as voltage-controlled voltage source. Alterna- 



tive opamps can be 1556 and 8007. — W. G. 
Jung, "IC Op-Amp Cookbook," Howard W. 
Sams, Indianapolis, IN, 1974, p 331-333. 




t must return lo ground via low-impedance dc path. 

*optional offset compensation, may be replaced with short in noncritical circuits. 



Ik 1k >- 
-vw*vw*- + 

1*0,022x0-011^ 



-O e out 



10-kHz LOW-PASS SALLEN-KEY— Article gives 
design equations from which values of com- 
ponents were obtained. Critical damping (Q = 
0.71) is provided. Frequency can be tuned over 
range of two decades by changing resistor val- 
ues simultaneously. Opamp can be one section 
of OP-11FY. For equivalent high-pass filter, 
transpose positions of resistors and capacitors. 
Gain is unity. — D. Van Dalsen, Need an Active 
Filter? Try These Design Aids, EDN Magazine, 
Nov. 5, 1978, p 105-110. 



100 kn Ria 
1 mF ±20% 1 1 mF ±20% 

-K — I K- 



I* 



2kn±5% 



WR3A 



2.2 MJ1 ±5% V 

11— wv- 



R2A 
100 kH 




1 Hz WITH 0.1-Hz BANDWIDTH— Three pots 
provides easy trimming to precise values de- 
sired. Use R2A to trim bandwidth to exactly 
0.100 Hz. Use R1A to trim gain to exactly 10.00. 
Finally, trim center frequency to exactly 
1 .000Hz. Adjustments are almost perfectly non- 
interacting if made in sequence given. — R. A. 
Pease, "Band-Pass Active Filter with Easy Trim 
for Center Frequency," Teledyne Philbrick, Ded- 
ham, MA, 1972, Applications Bulletin 4. 



0.022 ^F 




1-kHz VARIABLE-GAIN STATE-VARIABLE— 
Damping signal is inverted with fourth opamp 
to make gain and damping as well as frequency 
independently adjustable. Damping is in range 
of 0-2, with critical value of 1 .414 giving flattest 
response. For high pass, take output from first 



opamp; for bandpass, take output from second 
opamp. Value of input resistor is 10K (10,000 
ohms) when gain K is 1. — D. Lancaster, "Active- 
Filter Cookbook," Howard W. Sams, Indianap- 
olis, IN, 1975, p 135-136. 



e out 



100-Hz BANDPASS SALLEN-KEY— Uses one 
section of OP-11FY quad opamp or equivalent 
in circuit having Q of 4.7 and providing closed- 
loop gain of 200 or 46 dB. Opamp selected 
should have open-loop gain of 5 to 10 times re- 
quired gain at resonance. Adjust resistor values 
to tune center frequency. — D. Van Dalsen, Need 
an Active Filter? Try These Design Aids, EDN 
Magazine, Nov. 5, 1978, p 105-110. 



FILTER CIRCUITS — ACTIVE 



319 



■vw- 




1-kHz STATE-VARIABLE— Low-power filter 
uses three opamps to provide simultaneous 
high-, low-, and bandpass outputs. Article pre- 
sents complete design procedure for keeping 
current drain at minimum while providing de- 
sired gain-bandwidth product of 240 kHz. — L. 
Schaeffer, Op-Amp Active Filters — Simple to 
Design Once You Know the Game, EDN Maga- 
zine, April 20, 1976, p 79-84. 



Power dissipation 270 /iW 



-O BANDPASS 
OUT 



1 Hz-500 kHz VOLTAGE-TUNED BANDPASS— 
Coupling FET opamps with analog multiplier 
gives simple two-pole bandpass filter that can 
be tuned by external voltage of 0-10 VDC to 
give center frequency anywhere in range from 
1 Hz to 500 kHz with components shown. Article 
gives design equations. — T. Cate, Voltage Tune 
Your Bandpass Filters with Multipliers, EDN 
Magazine, March 1, 1971, p 45-47. 



SIGNAL INPUT E, O 



X-INPUT OFFSET 



TUNING c r\ 
INPUT "<-' 
-10V <E Z <0 



V-INPUT OFFSET 




OE„ OUT 



•FOR 1 Hz < f < 50 kH2, USE MODEL 3308/12C. 
FOR 50 kHz < f„ < 500 kHz, USE -MODEL 3402 




LOW-PASS AF— Can be used to attenuate un- 
desired high-frequency audio response in su- 
perhet or direct-conversion receivers having in- 
adequate IF selectivity, to improve CW or SSB 
reception. Resistor values determine cutoff fre- 
quency; 700 and 900 Hz are for CW and 2500 Hz 
for SSB. Insert filter at point having low audio 



level. Filter has input buffer, three cascaded ac- 
tive low-pass filter stages, and IN/OUT switch. 
Overall gain is unity. U1 is FairchiW /uA4136, 
Raytheon RC4136, or equivalent quad opamp. 
Overall response is 1.5 dB down at cutoff fre- 



quency, about 36 dB down at twice cutoff, and 
about 60 dB down at three times cutoff. R7 and 
R8 provide pseudoground of half supply volt- 
age, to eliminate need for negative supply. Will 
operate with supply from 6 to 36 V, drawing 
about 7 mA. — T. Berg, Active Low-Pass Filters 
for CW or SSB, QST, Aug. 1977, p 40-41. 



320 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




TRACKING 
FILTER OUTPUT 



3OK-i- 50O ''F 



DISCRIMINATOR 



9 Q-*/*f* 9 O OUTPUT (OPT I 



C r * COUPLING CAPACITOR 



1-MHz TRACKING FILTER— ExarXR-S200PLLIC 
is connected to function as frequency filter 
when phase-locked loop locks on input signal, 
to produce filtered version of input signal fre- 
quency at VCO output. Because circuit can track 
input over 3:1 range of frequencies around free- 



running frequency of VCO, it is known as track- 
ing filter. Optional wideband discriminator out- 
put is also provided. — "Phase-Locked Loop 
Data Book," Exar Integrated Systems, Sunny- 
vale. CA, 1978, p 9-16. 



■ Ot^F 



7.9 5 kXl 
V- o WV 



7.95 nil 



• — •— VS/i — • +%. 



.oi m fJ 



-oV„ 



|27Kfl 



;47kXi 



2-kHz LOW-PASS— Voltage-controlled voltage- 
source filter uses equal-value input resistors 
and equal-value capacitors, simplifying selec- 
tion of components. Equation for cutoff fre- 
quency then simplifies to f = 1/6.28RC or 1/ 
(6.28)(7950)(0.01)(10 s ). Opamp can be 741.— H. 
M. Berlin, "Design of Active Filters, with Exper- 
iments," Howard W. Sams, Indianapolis, IN, 
1977, p 85-86. 




OCTAVE AUDIO EQUALIZER— R2 provides up 
to 12-dB boost or cut at center frequency deter- 
mined by values of C1 and C2 as given in table. 
Uses Precision Monolithics OP-08 opamp. Low 
input bias current of opamp permits scaling re- 
sistors up by factor of 10, to reduce values of C1 



f (Hz) 


C1 


c 2 


32 


0.1 8mF 


0.018 M F 


64 


0.1 mF 


0.01»jF 


125 


0.047 m F 


0.0047 M F 


250 


0.022mF 


0.0022 tf F 


500 


0.012 M F 


0.001 2 M F 


Ik 


0.0056mF 


560pF 


2k 


0.0027 l iF 


270pF 


4k 


0.001 5^F 


150pF 


8k 


680pF 


68pF 


16k 


360pF 


36pF 



Ov„ 



and C2 at low-frequency end. Same circuit is 
used for all 10 sections of equalizer, which to- 
gether draw only 6 mA maximum from sup- 
ply. — "Precision Low Input Current Op Amp," 
Precision Monolithics, Santa Clara, CA, 1978, 
OP-08, p 7. 



.033 ^F 
o- II— 



C 4 
.033^ 



.033 f*.F 
-II- 



I0k& 



> 



2.22 ; 
kft 



1-kHz HIGH-PASS UNITY-GAIN— Passband 
gain of 741 or equivalent opamp circuit is set by 
ratio of C 4 to C, rather than by resistors. Values 
shown give unity gain for passband above 1-Hz 
cutoff. Circuit uses multiple feedback. — H. M. 
Berlin, "Design of Active Filters, with Experi- 
ments," Howard W. Sams, Indianapolis, IN, 
1977, p 100-102. 



6.8kfl 



V, o- 




1-kHz SIXTH-ORDER HIGH-PASS— Formed by 
cascading three different second-order sec- 
tions. Passband gain is 12.5 dB. Opamps can be 
741 or equivalent. Used when high rejection is 
needed for signals just below passband, in ap- 



plication where such rejection justifies cost of 
extra filter sections. — H. M. Berlin, "Design of 
Active Filters, with Experiments," Howard W. 
Sams, Indianapolis, IN, 1977, p 122-125. 



500-Hz LOW-PASS UNITY-GAIN— Multiple- 
feedback filter using 741 or equivalent opamp 
has unity gain in passband below 500-Hz cutoff . 
Resistors can be 5% tolerance. — H. M. Berlin, 
"Design of Active Filters, with Experiments," 
Howard W. Sams, Indianapolis, IN, 1977, p 99- 
100. 



FILTER CIRCUITS — ACTIVE 



321 



£,&■ 




AF NOTCH — Notch frequency is easily tuned at 
frequencies below 1 kHz with single capacitor 
C, or by replacing R, and R 2 with 249K pot. For 
higher frequencies, use 118 opamp for A, and 
5K for R 3 while lowering other resistances in 
proportion to R 3 . Indicated resistance toler- 
ances are necessary for optimum notch 
depth.— W. G. Jung, "IC Op-Amp Cookbook," 
Howard W. Sams, Indianapolis, IN, 1974, p 340- ' 
341. 



1.4-kHz TWIN-T BANDPASS— Combination of 
passive twin-T bandpass filter and 741 opamp 
gives simple audio filter for amplifying narrow 
frequency band (about 300 Hz wide) centered 
on 1 .4 kHz. Filter can be tuned to other frequen- 
cies by replacing R1 and R2 with 10K pots. Fre- 
quency is equal to 1/6.28RC where R is value in 
ohms of R1 and R2 and C is capacitance in farads 
of CI and C2. R3 is half of R1 .— F. M. Mims, "In- 
tegrated Circuit Projects, Vol. 2," Radio Shack, 
Fort Worth, TX, 1977, 2nd Ed., p 71-80. 



INPUTS 





NOTCH 



600-Hz NOTCH— With values obtained from de- 
sign equations and graph in article, state-vari- 
able or universal filter provides Q of 100 with 
four opamps. Notch filter is achieved by adding 
low-pass and high-pass outputs equally, for 
feed to dual-input summing amplifier. — H. M. 
Berlin, The State-Variable Filter, QST, April 
1978, p 14-16. 



322 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




•i O 



0.1 |iF 



f D "" 1 kHz, B * 1 kHz 

1-kHz BANDPASS— Simple circuit using volt- 1500 Hz.— 'The Linear and Interface Circuits 
age-follower opamp provides bandpass of 1 kHz Data Book for Design Engineers/' Texas Instru- 
centered on 1kHz, to give output range of 500- ments, Dallas, TX, 1973, p 4-39. 




01,02 2N2925, 2N339I, 2N3&6S 
03 2N27I2, 2N34I5, 2N3566 

"■BANDWIDTH 

CHOOSE L AND C FOR RESONANCE AT THE DESIRED FREOUENCY. 
FOR CENTER FREOUENCY OF 1000 Hz , USE 250 mH AND 0.1 jjF 



^R&MnwinTu 



1-kHz BANDPASS— Three-stage audio filter 
uses two series resonant circuits to give very 
narrow audio passband. Amount of feedback 



determines Q and bandwidth. 
Magazine, March 1974, p 89. 



-Circuits, 73 



r 




•o 

-o 



1-Hz BANDPASS — Single pot provides easy 
trimming to exact center frequency desired 
without change in bandwidth or gain. Q is 10. 
Design equations are given. — R. A. Pease, 
"Band-Pass Active Filter with Easy Trim for Cen- 
ter Frequency," Teledyne Philbrick, Dedham, 
MA, 1972, Applications Bulletin 4. 



Rl 

io Ma 



R2 

10 MS! 



C3 
540 






^n 



R3 
Mfi 



Lr__j 



fr 



1 



C1 C2 

270 pF 270 pF 



2JT-R1-C1 
R1 - R2 
CI - C2 



2R3 
C3 




t-16 counter 



CLOCK FOR COMMUTATING RC FILTER— Cir- 
cuit synchronizes multivibrator with line fre- 
quency to provide clock waveform required for 
switching capacitors electronically in n-path ac- 
tive filter for rejecting line frequency and har- 
monics up to fifth. Article gives complete circuit 



of active filter and describes operation. Clock 
serves to switch 16 MOSFETs on in turn for 
commutating 16 capacitors electronically at 16 
times line frequency. — K. F. Knott and L. Un- 
sworth, Mains Rejection Tracking Filter, Win- 
less World, Oct. 1974, p 375-379. 



60-Hz HIGH-Q NOTCH— Input network for 
SN72310 voltage-follower opamp provides at- 
tenuation of 60-Hz power-line frequency. Use 
high-quality capacitors for maximum Q. — "The 
Linear and Interface Circuits Data Book for De- 
sign Engineers," Texas Instruments, Dallas, TX, 
1973, p 4-39. 



940 pF f 



| SN72310 ' 



,470 pF 



e , ■ — out 



LOW-PASS WITH 10-kHz CUTOFF— Simple cir- 
cuit uses only one Texas Instruments SN72310 
voltage-follower opamp. For good temperature 
stability, use silvered mica capacitors. — "The 
Linear and Interface Circuits Data Book for De- 
sign Engineers," Texas Instruments, Dallas, TX, 
1973, p 4-39. 



FILTER CIRCUITS — ACTIVE 



323 




INPUT 



1-kHz CASCADED-OPAMP BANDPASS— Band- 
width of only 71 Hz is achieved by using four 
identical three-opamp filters in series, for in- 
creased selectivity in communication or RTTY 
receiver. Values for R1 and R2 are made variable 
for first filter stage, but pot is used for R3 in all 



four stages so they can be tuned to same center 
frequency. Batteries are used for supply, as filter 
draws only 17 mA.— F. M. Griffee, RC Active Fil- 
ters Using Op Amps, Ham Radio, Oct. 1976, p 
54-58. 





1-kHz THREE-FUNCTION— Uses National 
LM324 quad opamp, with appropriate biasing 
for single supply of +5 to +25 VDC. Values of 
R1 and R2 establish f c at 1000 Hz, while R3 gives 
Q of 50. Values of R1 and R2 for other bandpass 
center and cutoff frequencies f c can be calcu- 



lated from R = 15 x 10 7 /f c . Fourth opamp may 
be used as output amplifier or for summing 
high-pass and low-pass outputs. CI is same as 
C2. — P. A. Lovelock, Discrete Operational Am- 
plifier Active Filters, Ham Radio, Feb. 1978, p 
70-73. 




TUNABLE NOTCH — Opamp circuit requires 
only one pot (R,) to vary notch frequency. R 2 is 
used to set noise rejection to maximum. With 
values shown, filter tunes from 170 Hz to 3 kHz, 
with 3-dB bandwidth of 230 Hz and notch rejec- 



tion better than 40 dB over entire range. Circuit 
can be voltage-tuned by replacing R, with FET 
operated as voltage-variable resistor. — R. J. 
Harris, Simple Tunable Notch Filter, Wireless 
World, May 1973, p 253. 



19-kHz NOTCH— Used in commercial FM trans- 
mitters to eliminate 19-kHz program material 
from stereo encoder. Uses Optical Electronics 
9714 opamp in circuit that gives unity passband 
gain below center frequency, 0.7 gain above 
center frequency, and less than 0.001 gain at 
notch frequency. Provides adjustments for 
notch rejection level and Q. R1 is 84K, and R2 is 
36K in series with 10K pot.— "Precision Notch 
Filter," Optical Electronics, Tucson, AZ, Appli- 
cation Tip 10255. 



+15V 




TUNABLE NOTCH FILTER— Simple pot-tuned 
active notch filter has tuning range of 200 Hz in 
audio band and 3-dB rejection bandwidth of 10 
Hz, as required for tuning out whistle or power- 
line hum that is interfering with radio program. 
Article gives design theory for many other types 
of notch fitters.— Y. Nezer, Active Notch Filters, 
Wireless World, July 1975, p 307-311. 



324 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




Q MULTIPLIER — Article gives design procedure 
and equations for utilizing Q multiplication to 
simplify circuit for active bandpass filter. With 
values shown, center frequency is 3.6 kHz and 
Q of 10 is multiplied by gain of 6 to give effective 
Q of 60.— A. B. Williams, Q-Multiplier Tech- 
niques Increase Filter Selectivity, EDN Maga- 
zine, Oct. 5, 1975, p 74 and 76. 



q, 10 680 pF 



.0159 pF 



1-kHz FIFTH-ORDER LOW-PASS— Uses single 
first-order section and two different second- 
order sections to give passband gain of 10.3 dB. 
Opamps can be 741 or equivalent. — H. M. Ber- 
lin, "Design of Active Filters, with Experi- 
ments," Howard W. Sams, Indianapolis, IN, 
1977, p 119-122. 




«v 

I8k.fl 



I2k.fl 



SPEECH INPUT STAGE 



MICROPROCESSOR 
INTERFACE 



MICROPHONE 

CD 



3KHi LOW 
PASS FILTER 

r - 

PREAMPJ R 

I 



ICI : 

PIN I4:5V DC 
PIN 7:GND 



SPEECH RECOGNITION FILTER— Voice signal 
picked up by microphone is preamplHied and 
sent through 3-kHz low-pass passive filter C1- 
R1 to 1-kHz high-pass active filter and 1-kHz 
low-pass active filter using sections of LM3900 
quad opamp. Diode symbols on opamps indi- 




PARALLEL INPUT 



cate use of current mirrors for noninverting in- 
puts. Outputs are sampled about 60 times per 
second to implement speech recognition algo- 
rithm of computer, which counts number of 
high-pass and low-pass zero crossings per sec- 



ond and compares results with series of word 
models in memory to determine most likely 
match. — J. R. Boddie, Speech Recognition for 
a Personal Computer System, BYTE, July 1977, 
p 64-68 and 70-71. 



FILTER CIRCUITS — ACTIVE 



325 




320-Hz LOW-PASS— Frequency-dependent 
negative-resistance circuit uses 747 dual 
opamp. Signal source used as input should have 
low resistance, and load should have high re- 
sistance. Voltage-follower stages can be Used 
to isolate both input and output of filter.— R. 
Melen and H. Garland, "Understanding IC Op- 
erational Amplifiers," Howard W. Sams, Indi- 
anapolis, IN, 2nd Ed., 1978, p 104-105. 



VOLTAGE-TUNED STATE-VARIABLE— Pro- 
vides choice of high-pass, bandpass, and low- 
pass outputs, each with cutoff frequency vari- 
able between 1 and 6 kHz by varying control 
voltage between -10 V and +1SV. Output load 
resistor sets voltage gain between input and 
output. Gain-control input varies gain from 
maximum set by load resistor down to zero. 
Input signals must be limited to 100 mV be- 
cause input circuit is differential amplifier op- 
erating without feedback. — D. Lancaster, "Ac- 
tive-Filter Cookbook," Howard W. Sams, 
Indianapolis, IN, 1975, p 203-205. 




OI59/aF 




1-kHz THIRD-ORDER LOW-PASS— Circuit using 
741 or equivalent opamp consists of unity-gain 
first-order section followed by equal-compo- 
nent voltage-controlled voltage-source second- 
order section.— H. M. Berlin, "Design of Active 
Filters, with Experiments," Howard W. Sams, 
Indianapolis, IN, 1977, p 113-114. 



1-kHz BIQUAD BANDPASS— Three 741 opamps 
are connected to give two integrators and in- 
verter. Overall gain is -Q, determined by value 
of input resistor used. Circuit is tuned by vary- 
ing capacitors in steps. Absolute bandwidth re- 
mains constant as frequency changes. Chief ap- 
plications are in telephone systems, where 
identical absolute-bandwidth channels are re- 
quired.— D. Lancaster, "Active-Filter Cook- 
book," Howard W. Sams, Indianapolis. IN, 1975, 
p 159-164. 




' offset resistors may be replaced with shorts in noncritical circuits. 



■-Qe, 



326 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



«lnt 




r*x 



t must return to ground via low-impedance dc path. 

♦ optional offset compensation, may be replaced with short in noncritical circuits. 



1-kHz STATE-VARIABLE— Circuit using three 
741 opamps offers low sensitivity, voltage-con- 
trolled tun ing, and easy conversion to high pass 
or bandpass. For high pass, take output from 
first opamp. For bandpass, take output from 
second opamp. To increase frequency, change 
10K resistors to identical higher values. 10:1 re- 
sistance change produces 10:1 frequency 
change. Damping d is adjustable; critical value 
of 1.414 gives maximum flatness of response 
without overshoot. Design equations are 
given. — D. Lancaster, "Active-Filter Cook- 
book," Howard W. Sams, Indianapolis, IN, 1975, 
p 129-135. 



-90 



VARIABLE-BANDWIDTH AF— Audio filter using 
1000-Hz Wien bridge provides bandwidths from 
70 to 600 Hz. Transistors can be SK3004, GE-2, 
orHEP-254. — Circuits, 73 Magazine, Jan. 1974, 
p124. 




OOUT 



.0159/i.F 
-ir 




1-kHz THIRD-ORDER HIGH-PASS— Passband 
gain is 6 dB for Butterworth filter above 1-kHz 
cutoff. Damping factor is 1.000 for both sec- 
tions, each using 741 or equivalent opamp. — H. 
M. Berlin, "Design of Active Filters, with Exper- 
iments," Howard W. Sams, Indianapolis, IN, 
1977, p 115-116. 




output 

H O 



# denotes close tolerance 



20-2000 Hz VARIABLE BANDPASS— High-Q ac- 
tive bandpass filter can be adjusted over wide 
frequency range (100:1) while maintaining Q 
essentially constant over 100. Two-phase out- 
put is available. Opamps can be 741 or equiva- 



lent. Cascaded all-pass networks B and C each 
have to 180° phase variation and unity gain at 
all frequencies. These are driven by opamp A 
whose feedback signal is sum of input and out- 



put of all-pass networks. R 2 adjusts Q, and 
ganged log pots change center frequency. — J. 
M. Worley, Variable Band-Pass Filter, Wire/ess 
World, April 1977, p 61. 



FILTER CIRCUITS— ACTIVE 



327 




4.4K 



250-Hz THIRD-ORDER LOW-PASS— Values 
shown place cutoff at 250 Hz, with 1-dB dip in 
response curve. Input must be returned to 
ground with low-impedance DC path. — D. Lan- 
caster, "Active-Filter Cookbook," Howard W. 
Sams, Indianapolis, IN, 1975, p 146. 




200-400 Hz PASSBAND— Design is based on 
use of 3.2 for value of Q, to hold passband dip 
at 1 dB for two-pole filter. Multiple feedback is 
used for each pole. First opamp can be 741 or 
equivalent. Center frequency is 283 Hz. — D. Lan- 
caster, "Active-Fitter Cookbook," Howard W. 
Sams, Indianapolis, IN, 1975, p 166. 




5KI3Q-1) 
t must return to ground via low-impedance dc path. 



min op-amp open loop gain ■ 



— o BANDPASS OUTPUT 



GAIN-+Q 

PHASE - 90° 

AT RESONANCE 



1-kHz STATE-VARIABLE BANDPASS— With 
three 741 opamps or equivalent, circuit gain is 
Q (reciprocal of damping). Frequency is 
changed by changing 10K coupling resistors be- 
tween opamps while keeping their values 
equal. Increasing resistors 10 times increases 
frequency 10 times. High-pass output is ob- 
tained from first opamp and low pass from sec- 
ond opamp. — D. Lancaster, "Active-Filter Cook- 
book," Howard W. Sams, Indianapolis, IN, 1975, 
p 156-159. 




+ 12VQ- 



T 



-OPINH,UI,U2,U3 



-12 VO- 



| lOOV 






-OPIN 6,U1,U2,U3 



iff 

100V 



AF NOTCH — Center frequency of notch can be 
varied with single control R1; upper limit is 
about 4 kHz. Circuit Q and notch depth are con- 
stant over range. R2 is adjusted initially for best 
notch depth. All opamps are 741 14-pin DIP, 



such as Motorola MCI 741 L. U1 and U2 are in- 
tegrators with DC gain of about 2500, and U3 is 
summing device. Notch depth is at least 50 dB. 
Input to filter Is taken from loudspeaker or head- 
phone jack of receiver. High-impedance headset 



may be connected directly across output, or 
buffer stage can be added to drive lower-Imped- 
ance loudspeaker or headset. Use with AGC 
off. — A. Taflove, An Analog-Computer-Type Ac- 
tive Filter, QST, May 1975, p 26-27. 



328 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




V 



INPUT 50 t I IV 
O VA WV-* • 




rn 



INPUT 



♦optional 

■O OUT PUT - 30 e , n 
4.7K 440K 

0.033 for damping factor d. Opamps can be 
3-kHz STATE-VARIABLE BANDPASS— Design 741.— D. Lancaster, "Active-Filter Cookbook," VARIABLE Q AND FREQUENCY— Bandwidth 
is based on value of 30 for Q, corresponding to Howard W. Sams, Indianapolis, IN, 1975, p 166. can be made extremely sharp (less than 9 Hz) or 

very broad (greater than 300 Hz). Adjusting Qto 
change bandwidth also changes gain of filter. 
Center frequency of filter is independently ad- 
justable. — A. F. Stahler, An Experimental Com- 
parison of CW Audio Filters, 73 Magazine, July 
1973, p 65-70. 




12 (IB/octave ultimate slope 



27rR,i/£7^ 
100 kHz (as shown) 



100-kHz LOW-PASS UNrTY-GAIN— Opamp 
serves as active element in voltage-controlled 
voltage-source second-order filter. Other 
opamps having required high input resistance, 
low input current, and high speed are 1556 and 
8007.— W. G. Jung, "IC Op-Amp Cookbook," 
Howard W. Sams, Indianapolis, IN, 1974, p 331- 
333. 




REJECTION FREQUENCY = f„= 225.8 Hz 



225.8-Hz REJECTION— Provides extremely supplies. Article gives equation for transfer Minimum Component Count, EON Magazine, 
sharp adjustable-depth notch with only two function.— R. Carter, Sharp Null Filter Utilizes Sept. 20, 1976, p 110. 
low-gain opamps. Suitable for single-ended 



FILTER CIRCUITS — ACTIVE 



329 



einO 




I — vvv — T 
J, 39. 2K 



. 016 (if 



— IH- 

.016mF 



JIOK 



39. 2K 




J10K 



e out 



1-kHz HIGH-PASS FLATTEST-RESPONSE— Val- 
ues are chosen for flattest possible response 
obtainable with third-order configuration of 
two 741 opamps. Tripling capacitance values 
cuts cutoff frequency by one-third and vice 
versa. Component tolerance can be 10%. Gain 
is 2.— D. Lancaster, "Active-Fitter Cookbook," 
Howard W. Sams, Indianapolis, IN, 1975, p 186. 



2.4-kHz LOW-PASS/HIGH-PASS— Three 741 
opamps are connected to provide separate low- 
pass and high-pass outputs simultaneously for 
complex synthesis problem requiring state-var- 
iable filter. Gain is 1.— D. Lancaster, "Active-Fil- 
ter Cookbook," Howard W. Sams, Indianapolis, 
IN, 1975, p 192-193. 





100K QUAD POT AUDIO TAPER 



O0UTPU 




RANGE 


C 


1-lOHz 


1.600 U F 


10 -100 Hz 


0.160uf 


100-lOOOHz 


0. 016 uF 


l-10kHz 


1600 pF 


I0-I00kHz 


160 pF 



TUNABLE FOURTH-ORDER LOW-PASS— Use 
of four ganged pots permits varying cutoff fre- 
quency over 10:1 range. Table gives ranges ob- 
tainable with five different values for C. Opamps 
can be 741 or equivalent. Tracking of 5% for 
pots calls for expensive components, but ordi- 
nary snap-together pots may prove satisfactory 
If tuning range is restricted to 3:1 or less and 
more capacitor switching is used. — D. Lancas- 
ter, "Active-Filter Cookbook," Howard W. 
Sams, Indianapolis, IN, 1975, p 195-197. 



AF LOW-PASS FOR CW— Design using 10% tol- 
erance components gives sufficiently wide 
bandwidth while maintaining steep skirt re- 
sponse for CW reception in direct-conversion 
communication receiver. Filter has five identical 




' |^~~° vfl 
o fir9 



three-transistor sections, each peaked at cutoff 
frequency. Q of each section is about 1.9, which 
gives 6-dB bandwidth of about 200 Hz. With 
center frequency at 540 Hz, attenuation is 75 dB 
at 1200 Hz. Net gain of system is 28 dB at res- 



onance. NPN transistors are 2N3565, 2N3904, or 
similar; PNP transistors are 2N3638, 2N3906, or 
similar.— W. Howard, Simple Active Filters for 
Direct-Conversion Receivers, Ham Radio, April 
1974, p 12-15. 



330 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



lOkft 
-AAA— 



lOkfl 



*** i x^ 



. 0159/1 F 




2.2 kft 



I5ktt 





1-kHz FOURTH-ORDER HIGH-PASS— First sec- "Design of 

tion is second-order high-pass filter having gain Howard W. 

of 1.2 dB, and second section has gain of 7 dB. 117. 
Opamps are 741 or equivalent. — H. M. Berlin, 



Active Filters, with Experiments," 
Sams, Indianapolis, IN, 1977, p 116- 



800-Hz BANDPASS— Active filter has 800-Hz 
center frequency for optimum CW reception. 
Bandwidth is adjustable. Back-to-back diodes 
provide noise-limiting capability. — U. L. Rohde, 
IF Amplifier Design, Ham Radio, March 1977, p 
10-21. 



1.8-1.9 MHz 



1.8-1.9 MHz BANDPASS— Butterworth band- 
pass filter, suitable for use with broadband 
preamp, helps reject out-of-band signals. Filter 
also protects preamp from signals across re- 
sponse range from broadcast band through 
VHF. C1 and C2 are mica trimmers. L1 and L2 
have 30 turns No. 22 enamel on Amidon T68-6 
toroid cores to give 5.1 /tH. — D. DeMaw, Beat 
the Noise with a "Scoop Loop," QST, July 1977, 
p 30-34. 



I 68 

> I Q " 220 f 

■>qr L,fJ 



50 
S.M. 

1 t-Hf-T T 



8WL -100kHz I 
IL-0.5<)B |_ 
fo- 1.85 MHz 



_«rci 
7^200 



-1- 1000 -1- 1000 
' S.M. "T* S.M. 

■m 4- 



rrn 



-KC2 
-200 



■ . 1 

68 | 

H 

' 220 

H 



Efe 



x 



S.M. - SILVER MICA 



*- FEEDBACK 



CI C2 02 

.005 005 



R4 £62K 

SELECTIVITY 



Rl 50K 

rr 



-^Hrr 



R2 50K 



m 



1 47fl 

< t-AVV W\ 1 



Tu | 680 

I6K' 'TVOI 

t 1 * * 



330K 
@-w. — 1 



I00K 



► 15 

4- 



470 K 



68ok 

S68K 



, J_l( .LINE TO 

^\ K„ V.C Jl PHONES 




I.O^F 
25V 



VARIABLE-Q AF— Consists of tuned amplifier 
having inverse feedback, connected so band- 
width at -6 dB is variable from 50 to 400 Hz for 
center frequency of 1 kHz. Improves selectivity 
of amateur receivers. Audio from receiver is ap- 
plied to inverter Q3 through Q1 . Part of inverted 



signal is fed back to twin-T network R1-R2-R3- 
C1-C2-C3 which has high impedance to ground 
except at its resonant frequency. Unattenuated 
signal goes through Q2 for adding to uninverted 
output at base of 03. Degree of cancellation by 
two out-of-phase signals feeding 03 is con- 



trolled by R4 to adjust selectivity. Filtered out- 
put is boosted by 04 and Q5. Article covers con- 
struction, calibration, and operation. Q1-Q6 are 
GE-20, and Q7 is GE-14 or GE-28. — C. Town- 
send, A Variable Q Audio filter, 73 Magazine, 
Feb. 1974, p 54-56. 



FILTER CIRCUITS — ACTIVE 



331 




.0047^F^: 



600-Hz THIRD-ORDER LOW-PASS— Butter- 
worth filter using 741 or equivalent opamp pro- 
vides gain of 6 dB in passband below 600-Hz cut- 
off. All components can be 5% tolerance. — H. 
M. Berlin, "Design of Active Filters, with Exper- 
iments," Howard W. Sams, Indianapolis, IN, 
1977, p 114-116. 




oe ou i 



t must return to ground via low-impedance dc path. 

SECOND-ORDER 1-kHz LOW-PASS— Circuit 
using 741 opamp has equal-value series input 
resistors and high-pass capacitors. Cutoff fre- 
quency can be increased by changing 10K resis- 
tors to higher values while keeping their values 
identical. 10:1 resistance change provides 10:1 
frequency change. Damping d is adjustable; 
critical value of 1.414 gives maximum flatness 
of response without overshoot. Interchange 
10K resistors and 0.016-/*F capacitors to convert 
circuit to 1-kHz high-pass filter.— D. Lancaster, 
"Active-Filter Cookbook," Howard W. Sams, In- 
dianapolis, IN, 1975, p 127-129. 



ci 



R2 
-VW- 



Vref 



1-kHz BANDPASS/NOTCH— Biquad filter uses 
all four sections of LM324 quad differential- 
input opamp to provide choice of bandpass and 
notch outputs. Supply voltage range can be 3- 
32 V, with reference voltage equal to half of sup- 
ply value used. For center frequency of 1 kHz, R 
is 160K, C is 0.001 /ttF, and R1-R3 are 1.6 meg- 



Vref 



ohms. Coupling capacitors CI can be 10 times 
value used for C— "Quad Low Power Opera- 




-0 Notch Output 



tional Amplifiers,' 
DS9339R1. 



Motorola, Phoenix, AZ, 1978, 



AUDIO SUFFER 



FILTER SECTION 



DETECTED 

AUDIO O H 

INPUT 




AUDIO AMPLIFIER 




NOTE ALL RESISTORS 1/2 WATT 
5% CARBON COMPOSITION. 
Ul , U2, U3 ARE FX-60 

BANDPASS FOR CW-Sophisticated audio pro- Bandwidth is about 150 Hz. Minimum relative and FS-61 production by manufacturer).-M. A. 

cessing system for CW bandpass, using com- attenuation is above 20 dB. Uses three Kinetic Chapman, Audio Filters for Improving SSB and 

munication receiver, has actual bandpass cen- Technology FX-60 ICs (culled from FS-60, FS-6S, CW Reception. Ham Radio, Nov. 1976, p 18-23 
ter frequency between 900 and 950 Hz. 



332 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




10-MHz TRACKING— Connection shown for 
560N PLL tracking filter uses crystal to keep 
free-running frequency at desired value for sig- 
nals near 10 MHz. Lock range varies with input 
amplitude, from about 0.3 kHz for 1 mV P-P 
input to about 3 kHz for 100 mV P-P.— "Signet- 
ics Analog Data Manual," Signetics, Sunnyvale, 
CA, 1977, p 850-851. 



INPUTO ^A/V- 




2k 20k 200k 



700-2000 Hz TUNABLE BANDPASS— Uses RC 
notch circuit as feedback element for active-fil- 
ter opamp. With tuning pot set for center fre- 
quency of 1000 Hz, 3-dB bandwidth is 23 Hz and 
10-dB bandwidth is 68 Hz. At 1000 Hz, voltage 
gain is 36 dB. High-frequency rolloff is good, 
being 43 dB down at 2000 Hz, so circuit converts 
1000-Hz square wave into sine wave. Article 
gives design equations.— C. Hall, Tunable RC 
Notch Filter, Ham Radio, Sept. 1975, p 16-20. 



INPUT 
O 



-3H 



— W\r— 






-OHh-MSS 
OUT 



5004 39k 



OJJOI 



Qour 



toot 



300-3000 Hz TUNABLE FOUR-FUNCTION— 
Provides choice of high-pass, bandpass, low- 
pass, and tunable notch outputs. Uses National 
LM324 quad opamp. Tuning pots are ganged 
500K 2-W carbon with reverse log taper. Notch 



ui ^ — — ■ 



' OLO-PASS 

OUT 



SOOk 39k 



I U3 ^2 *— -VW- 



100* 



of -35 dB is 200 Hz wide at -3 dB points. Notch 
output has unity gain with respect to input sig- 
nal, but other three outputs provide gain. — P. 
A. Lovelock, Discrete Operational Amplifier Ac- 
tive Filters, Ham Radio, Feb. 1978, p 70-73. 



too* 



£> 



to : 



rh 



"■' NOTCH 

")r— -p 



too* 
-vw- 



+15 V 

o 



v 0UT 




N-PATH FILTER - 



1-kHz BANDPASS HIGH-Q— Shunt-switched 

bandpass filter with Q of 1000 and voltage gain cuits, and decode logic for 8-path filter. Band- controls shunt-switched filter action.— Analog 

of about 7 uses DG508 CMOS multiplexer con- width for 3 dB down is 1 Hz centered on 1 kHz, Switches and Their Applications," Siliconix, 

taining required analog switches, interface cir- with asymptotic slope of 6 dB per octave. Clock Santa Clara, CA, 1976, p 5-12-5-14. 



CHAPTER 28 

Filter Circuits — Passive 



Includes low-pass, high-pass, and bandpass AF filters for improving reception 
of voice, CW, SSB, and RTTY signals, along with higher-frequency circuits for 
suppressing broadcast-band interference in communication receivers and 
minimizing other types of interference. 




i r i 



T 




r 



.029 .012 .0145 



q-v 492 sjsttOO 7p 

44 ilH 0? P H 
-YYV\, 

690 



3.5 pH >-3.e yH 




•-j-N.056 ^-p.C 



TM 

r r ' i 

0.54 *M 0.46 uH 

•YYV\ 

/oa 



.022 930 ON 

'£-H*-r-K- 



2.6 pH ^-2.8 „H 



043 •-t-s .0233 



T 




xx 



D — »0 



I 



0/35 560 700 



r r i 



^.027 ^-r-^.0/4 



0.6 iiH 0.3 pH 



T 



i i r 

4 pN 0.2 >>H 



XX 

J( ; l (; I f- 



900 37/ 450 



W« ^ (.2 pH 




x r 



r r " t 



5O0 210 254 



zg £0.6jjH >0.63>iH 



ST*-.IOOO ^r^5: 



ELLIPTIC HIGH-PASS/LOW-PASS— Covers 1.45 
to 32 MHz in six steps, for use at front end of 
high-frequency communication receiver to sup- 
press unwanted broadcast signals. Low-pass 
filter section, acting with one of six following 
low-pass sections, gives over 90-dB image 
suppression. Special Bessel-Cauer elliptic filter 
having Chebyshev response in passband pro- 
vides required 50-ohm impedance matching so 
filters can be cascaded. — U. L. Rohde, Optimum 
Design for High-Frequency Communications 
Receivers, Ham Radio, Oct. 1976, p 10-25. 



333 



334 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




INPUT O f- 



X 



5O0 5k 50k 



50.5-MHz BANDPASS— Provides 60% band- 
width with only 4-dB insertion loss. Each coil is 
about 2.2 iM, and trimmer capacitors are 1 .5-7 
pF. Sweep signal generator and 5-in CRO are 



10 

i-WV-i 



FILTER 
St !«"" 



O 22mHf 



I 



HI 
S2 



LO 
J FREQ. 



CW FILTER FOR INTERFERENCE— Audio band- 
pass filter, designed for connection between 
loudspeaker jack of receiver and external loud- 
speaker or phone, has half-power bandwidth of 
about 70 Hz but rolls off gradually without caus- 
ing ringing. Series LC combination, connected 
in hot line to loudspeaker, looks like 5-ohm re- 
sistance at resonance, cutting signal amplitude 
about in half. At lower frequencies filter looks 



essential for alignment.— P. H. Sellers, 50-MHz 
Bandpass Filter, Ham Radio, Aug. 1976, p 70- 
71. 




Jt 
-o v/ 



J2 

-o v/ 



SPEAKER 



JT 



like large capacitive reactance and at higher fre- 
quencies it resembles large inductive reactance, 
both causing high attenuation. Filter thus dis- 
criminates against all except switch-selected 
resonant frequency, either 760 or 1070 Hz. 
Choose best frequency for particular receiving 
situation by trial.— F. Noble, A Passive CW Filter 
to Improve Selectivity, QST, Nov. 1977, p 34- 
35. 



60-Hz TUNABLE NOTCH— Can be used to min- 
imize hum pickup from AC line. Circuit tunes 
from 40 to 120 Hz with single pot. Article gives 
design equations. With unmeasured ceramic 
disk capacitors and 5% resistors, notch depth 
at 60 Hz was 44.5 dB. By selecting capacitors 
with equal values and replacing 333K with 500K 
trimpot, careful adjustment increases notch 
depth to 57 dB.— C. Hall, Tunable RC Notch Fil- 
ter, Ham Radio, Sept. 1975, p 16-20. 



IN-.— -»0UT 




BANDPASS FOR CW— Provides bandwidth of 
about 400 Hz (3 dB down) centered on 875 Hz, 
for improving reception of CW signals with am- 
ateur receiver. Uses three 44-mH toroids. — D. C. 
Rife, Low-Loss Passive Bandpass CW Filters, 
QST, Sept. 1971, p 42-44. 



m 



7y r ^E, ^ ? c r 'Tm 



m rh rn rn rn m 



-X- 



^} 



T\ 



M.7&.~7&.7&. 



/T7 rn rn n? rn rt! 




33 turns no. 20 enamelled on Amid'on 
T-106-2 toroid cores (approximately 
14 |UH). Links are each 2 turns 
6 turns no. 20 enamelled on Amidon 
T-30-2 toroid core 



C 4-section air variable, 10-160 pF per 

section 
Ct 35-pF trimmer capacitors 



160-METER BANDPASS— Four-resonator filter 
is tunable from 1.8 to 2 MHz and has insertion 
loss of 5 dB. 3-dB bandwidth is 30 kHz, and 6- 



60 dB shape factor is 4.78. Stopband attenua- 
tion is over 120 dB. Key to high performance is 
use of high-Q toroid cores. Article covers the- 



ory, construction, and adjustment. — W. Hay- 
ward, Bandpass Filters for Receiver Preselec- 
tors, Ham Radio, Feb. 1975, p 18-27. 



FILTER CIRCUITS — PASSIVE 



335 



DIODE-SWITCHED FOUR-CRYSTAL IF FILTER— 
Application of 9-12 VDC to control points A or 
B gives choice of two different selectivities for 
IF amplifier in amateur communication receiver. 
For 500-Hz bandwidth at 455 kHz, frequencies 
of crystals in use should be 300 Hz apart for CW, 
1.8 kHz apart for 2.7-kHz SSB bandwidth, and 
1.25 kHz apart for 2.1 -kHz SSB bandwidth. Ar- 
ticle gives design graphs.— J. J. Schultz, Eco- 
nomical Diode-Switched Crystal Filters. CO. 
July 1978, p 33-35 and 91. 



Input 
> 1(- 



5.6K; 



Y1A 1N458 (all) Y1A 

-0 t * 



15KJ 



Y2A 
- Q t H 



5.6K 



-o- 



Y2A 

K t 0- 



1 



TO 



1 I 



*4— ■ — w- 



15K . 



Y1B 

-HO , ► 



Y2B 



Y1B 

w r - 



Output 

H( > 



Af 



■^v 



-> +9 to 12v.d.c. 




2125-Hz LOW-PASS— Used with AFSK keyerto 
convert 2125-Hz square wave to sine wave by 
removing third and fifth harmonics. All three 
coils are toroids, with its two windings in series 
for 88 mH and in parallel for 23 mH.— L. J. Fox, 
Dodge That Hurricanel, 73 Magazine, Jan. 1978, 
p 62-69. 




FOUR-CRYSTAL FILTER— Uses two matched 
sets of crystals, with each pair having maximum 
frequency difference of 25 Hz. Transistors serve 
as input and output isolating stages. Each 
matched pair, such as A-A', should be from 
same manufacturer and have same nominal 
parallel capacitance for circuit, same activity, 
and same resonant frequency within 25 Hz. Ar- 



ticle gives detailed instructions for grinding 
crystal to increase resonant frequency when 
necessary for matching. Use frequency counter 
for checking frequency. Values given in circuit 
are for 5.645-MHz crystal filter with -6 dB band- 
pass of 1.82 kHz and insertion loss of about 5 
dB. Crystals used are 5.644410 MHz and 



5.644416 MHz for A and A', and 5.645627 MHz 
and 5.645641 MHz for B and B'. Coil has 7 + 7 
turns No. 28 enamel bifilar wound on 10.7-MHz 
IF transformer having 2.4-mm slug diameter. C p 
is 39 to 47 pF.— J. Perolo, Practical Considera- 
tions in Crystal-Filter Design, Ham Radio. Nov 
1976, p 34-38. 



336 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Input 

> — K- 



Y1A 



1N458 

— H— 



15k; 



Y2A 

— 0- 



5.6KJ 



Output 



>5.6K 



Shield 

1 



,r 



H 



1 I I 



-Q- 



15k; 



Y1B 



I 



1 ; 


L 1 1 
r s • 


I 


1 l 


* 1 , 
1 



I I 

Alternate tuned 
circuit arrangement 




DIODE-SWITCHED CRYSTALS— 1N458 diodes 
switch crystals in pairs to provide two different 
degrees of selectivity for 455-kHz IF filter. For 
SOO-Hz bandwidth in amateur communication 
receiver, spacing between crystal frequencies 
should be 300 Hz, which is obtained with 



455.150 kHz for Y1A and 454.850 kHz for Y1B. 
Provides adequate CW selectivity for trans- 
ceiver having good SSB filter. — J. J. Schultz, 
Economical Diode-SwKched Crystal Filters, CO, 
July 1978. p 33-35 and 91. 




C1.C6 50 pF APC or MAPC variable 
C2,C3 67 pF ±5%, 7500 working volts dc 
C4.C5 (Centralab type 850S ceramic capa- 
citor, 6 for $1.00 from John Meshna, 
P.O. Box 62, E. Lynn, Massachu- 
setts 01904) 
L1.L5 0.2 flH, 3 turns no. 16 or no. 14 
enamelled, Vz inch (13mm) ID, spac- 
ed 1/8 inch (3mm) per turn 
L2.L4 0.3 jUH, 5V2 turns no. 14 enam- 
elled, »/2 inch (13mm) ID, spaced 
1/8 inch (3mm) per turn 
L3 0.38 fiH, 7 turns no. 14 enamelled, 

V; inch (13mm) ID, spaced 1/8 inch 
(3mm) per turn 

LOW-PASS WITH 42.5-MHz CUTOFF— De- 
signed for insertion in antenna coax of amateur 
radio station up to 1 kW, to cure TVI problems. 
Provides 60-dB attenuation on channel 2. Filter 
uses m-derived terminating half-sections at 
each end, with two constant-K midsections. 
End sections are tuned either to channel 2 (55 
MHz) or channel 3 (61 MHz). Article covers con- 
struction and tune-up. — N. Johnson, High-Fre- 
quency Lowpass Filter, Ham Radio, March 1975, 
p 24-27. 



2.955-MHz HIGH-PASS— Used in offset fre- 
quency-measuring system for amateur-band 
signals. Nine-section Chebyshev high-pass fil- 
ter with 1-dB passband ripple attenuates un- 
desired 2.045-2.245 MHz image 16 dB while se- 
lecting desired 2.955-3.155 MHz signal. Filter 



"2 

has sharper cutoff characteristic, for given num- 
ber of sections, than Butterworth or image pa- 
rameter designs.— J. Walker, Accurate Fre- 
quency Measurement of Received Signals, Ham 
Radio, Oct. 1973, p 38-55. 



4-OHM T 
INPUT I 




V 



4-OHM 
OUTPUT 

-iv o- 



" — ^Ym_^ 



1 



fc_T a 




rrrr\ 



D 



<v 




VOICE BANDPASS— Used between 8-ohm out- 
put of communication receiver and 8-ohm loud- 
speaker or low-impedance phones, to suppress 
Continuous Random Unwanted Disturbances 
on voice transmissions. Passband is 355 to 2530 



Hz at 3-dB points. L1 and L3 are 44-mH toroids. 
L2 is 88-mH toroid with 94 turns removed. T1 
and T2 are 88-mH toroids with 100 turns No. 28 
enamel wound over original winding of each for 
primary.— R. M. Myers, The SSB Crud-O-Ject, 
QST, May 1974, p 23-25 and 56. 



Li 

607mH 
=2 

HI- 

035/jF 



;o 319;jF 



X 



64 28mH 

HI— ' 

098/jF 



;0 431juF 



J0 269 



l_i 253 turns 28 swg 35mm VINKOR LA1211 

L1-C2 Tune to 3kHz 

L 2 226 turns 28 Swg 35mm VINKOR lA12!I 

L 2 -C 4 Tune to 2kH2 

1-kHz FIFTH-ORDER LOW-PASS— Used with 1- 
kHz signal generator to remove unwanted har- 
monics, leaving pure sine wave as required for 
measuring distortion in modem audio ampli- 
fiers. Attenuation peaks are carefully positioned 
to coincide with second and third harmonics, 
giving 65-dB attenuation of these harmonics 
and at least 50-dB attenuation of higher har- 
monics.— J. A. Hardcastle, 1 kHz Source Clean- 
ing Filter, Wireless World, Oct. 1978, p 59. 



FILTER CIRCUITS — PASSIVE 



337 



70.738 



53.284 



70.738 



500- 
600J"L 



/rrY^i^frr^^ffn^^^ 




225-Hz BANDPASS RTTY— Used ahead of lim- 
iter in 170-Hz-shift RTTY receiving converter. 
Chebyshev mesh configuration with 0.1-dB rip- 
ple uses inductor to ground for sharpening 
lower skirt, with capacitive coupling for sharp- 
ening upper skirt, to give good symmetry for 
response curve. Capacitors should be high-Q 



500- 
600.TL 



types, well matched. Take turns off inductors as 
required to move passband higher if initially 
low in frequency. Insertion loss is 6.6 dB and 3- 
dB bandwidth is 225 Hz, which makes mark and 
space tones only 1.5 dB down. — A. J. Klappen- 
berger, A High-Performance RTTY Band-Pass 
Filter. QST, Jan. 1978, p 33. 




693-2079 Hz TUNABLE NOTCH— Requires only 
one tuning pot to cover entire frequency range. 
Developed for use in tunable narrow-band 
audio amplifier. Article gives design equations. 
Depth of notch is greater than 50 dB. Doubling 
capacitor values changes tuning range to 355- 
1 028 Hz, while cutting values in half gives range 
of 1340-4110 Hz.— C. Hall, Tunable RC Notch 
Filter, Ham Radio, Sept. 1975, p 16-20. 




fco-1.65MHz 



AM BROADCAST REJECTION— Seven-element 
m-derived high-pass filter provides 30-dB rejec- 
tion at AM broadcast-band frequencies while 
passing signals in 160-meter band. Midsection 
m-derived branch of circuit was eliminated to 
simplify construction, but can be added and 



tuned to particular broadcast station that pre- 
sents difficult interference problem. LI and L3 
are 40 turns No. 30 enamel wound on T50-2 
powdered-iron toroid. L2 has 22 turns No. 30 on 
T50-2 core. — D. DeMaw, Low-Noise Receiving 
Antennas, QST, Dec. 1977, p 36-39. 




ne- 



- ' ^c„ 



rh rh rh rh rh 

L 35 turns no. 22 enamelled on Arnidon 

T-68-2 toroid cores (7 flH). Input link 
is 4 turns, output link is 3 turns 

80-METER BANDPASS— Four-resonator filter 
for use in 80-meter amateur band has 100-kHz 
bandwidth, 4.4-dB insertion loss, and 6-60 dB 
shape factor of 5.16. Filter was designed and 
aligned at 3.75 MHz; realignment at 3.6 and 3.9 




rh rh rh rh 

C 210 pF, 1% silver mica 

Cy 60-pF mica compression trimmers 

MHz yielded similar results. Article covers the- 
ory, construction, and adjustment.— W. Hay- 
ward, Bandpass Filters for Receiver Preselec- 
tors, Ham Radio, Feb. 1975, p 18-27. 




m 



m 



SWITCHABLE AF FILTER— Provides wide range 
of switch-selected capacitor values for varying 
cutoff frequencies, to permit use of filter for 
either phone or CW reception. On CW, circuit 
improves reception by eliminating higher fre- 
quencies that are largely interference.— J. J. 
Schuftz, The Quiet Maker, 73 Magazine, March 
1974, p 81-84. 



° 1— 1 nnnn » * nrv-^ — , . rvw . , ,- 

_J_0./jifJ_I.0,F _1_O.2j,f_L.Z.0jjF I 0.2.F | ;o,f J Q ,, F I | Q, f 

- T M-V-T-V4- T 



LOW-PASS PI-SECTION AF— Four-pole double- 
throw switch gives choice of 650-Hz cutoff for 
CW or 2000 Hz for SSB. Filter capacitors are 
matched. Response decreases continuously be- 



yond cutoff frequency, with no loss of atten- 
uation.— E. Noll, Circuits and Techniques, Ham 
Radio. April 1976, p 40-43. 



CHAPTER 29 

Fire Alarm Circuits 



Sensors used may respond to gas, ionization, flame, or smoke associated 
with fire, for triggering circuits driving variety of alarm devices. 



-W ir- 




I 



1.5 k 
1W 



~f 



MPS6&6& 
4.7 k y^ 

— w\ — • — [pi 










"/ 2N6070A 
_/ Q2 



:iomf < 47 k 



TRIAC GAS/SMOKE DETECTOR— Conductivity 
of Taguchi TGS308 gas sensor increases in pres- 
ence of combustible gases, increasing load volt- 
age across R1 from normal 3 VRMS to as much 
as 20 V. Rise in voltage trips comparator to turn 
on transistor Q1 that supplies trigger current to 
2N6070A sensitive-gate triac. Resulting full- 
wave drive of Delta 16003168 24- VAC horn gives 
sound output of 90 dB at 10 feet. Horn stops au- 
tomatically when gas clears sensor. — A. 
Pshaenich, "Solid State Gas/Smoke Detector 
Systems," Motorola, Phoenix, AZ, 197B, AN- 
735, p 4. 



15V O- 



T6S-202 DETECTOR* 



HEATER 




•AVAILABLE FROM 

FIGARO ENGINEERING 
OSAKA, JAPAN 
3 15 6 HIGASHITOYONAKA 
TOYONAKA CITY 

GNDO 



GAS/SMOKE SENSOR— Sensor is based on se- 
lective absorption of hydrocarbons by N-type 
metal-oxide surface. Heater in sensor bums off 
hydrocarbons when gas or smoke disappears, 
to make sensor reusable. Requires initial warm- 
up time of about 15 min in hydrocarbon-free en- 



vironment. When gas or smoke is present, V, 
quickly rises and triggers programmable UJT 
Q,. Resulting voltage pulse across R 4 triggers Qj 
and thereby energizes buzzer. S, is reset switch. 
R, and C, give time delay that prevents trigger- 



ing by small transients such as smoke from cig- 
arette. R 5 adjusts alarm threshold. Use regu- 
lated supply. — S. J. Bepko, Gas/Smoke 
Detector Is Sensitive and Inexpensive, BDN 
Magazine, Sept. 20, 1973, p 83 and 85. 



338 



FIRE ALARM CIRCUITS 



339 




R1 
300 kM 



Q4 
MPS-A14 



IONIZATION ALARM USING TRANSISTORS— 
Use of continuous smoke alarm signal rather 
than beeping hom simplifies transistor circuits 
needed to trigger fire alarm and low-battery 
alarm. When high impedance of ionization 
chamber is lowered by smoke or gas, amplifier 



01-02-03 supplies 100-/* A base current to Dar- 
lington 04 for powering horn continuously as 
long as smoke content exceeds that set by 
threshold control R5. Low-battery circuit is 
tripped at voltage range between 9.8 and 11.2 
V, as determined by R13, to energize MVBR 08- 



09 for driving horn 0.7 s, with 50-s OFF intervals. 
Battery is chosen to last at least 1 year while 
furnishing standby current of about 70 /xA.— A. 
Pshaenich, "Solid State Gas/Smoke Detector 
Systems," Motorola, Phoenix, AZ, 1975, AN- 
735. p 8. 



-+12.5V 




MZ4625 



220 kfi 



-r- 



2N4403 



D 4 H 1N9H 

— o- 



^ 22 Mfi * 




] Ikfil 



IONIZATION-CHAMBER SENSOR— MOSFET Q, 
with high input impedance monitors voltage 
level at divider formed by R, and ionization 
chamber, with output of Q, going to Qj which 
forms other half of differential amplifier. With 
smoke level of 2% or higher, Q 3 is turned on and 
applies logic 1 to one input of NAND gate 1 in 



-X 



Imp 




0.1 mF 



asymmetrical astable MVBR. Capacitor in 
MVBR charges quickly and discharges slowly, 
making alarm hom sound during discharge via 
inverter 3 and driver transistor Q 4 . Comparator 
circuit Qs drives second MVBR to energize hom 
through inverter 6 and same driver Qu when bat- 



tery is low, but with distinctive 1-s toot every 
23 s to conserve energy remaining in battery 
and differentiate from fire warning. — A. 
Pshaenich and R. Janikowski, Gas and Smoke 
Detector Uses Low-Leakage MOS Transistor, 
Electronics, Nov. 28, 1974, p 124-125. 



340 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




24 vac Horn 
Delta 
16003168 



SCR GAS/SMOKE DETECTOR— Simple circuit 
uses Taguchi TGS308 gas sensor with SCR Q1 
for half-wave control of 24-VAC alarm horn. 
Sensor is based on adsorptive and desorptive 
reaction of gases on tin oxide semiconductor 
surface encased in noble-metal heater that 
serves also as electrode. Combustible gases in- 
crease conductivity of sensor, thereby increas- 
ing load voltage enough to trip comparator and 
initiate alarm. Output voltage across R1 is nor- 
mally about 3 VRMS. With gas or smoke, volt- 
age can rise to 20 V. When gas or smoke has 
cleared sensor, SCR turns off at first zero cross- 
ing. Drawbacks are absence of time delay for 
preventing false alarm when power is turned on 
and reduced sound level of horn with half-wave 
operation. — A. Pshaenich, "Solid State Gasl 
Smoke Detector Systems," Motorola, Phoenix, 
AZ, 1975, AN-735, p 3. 



FLAME DETECTOR DRIVES TTL LOAD— Sensor 
is silicon Darlington phototransistor Q, having 
peak response near infrared bands. Filter is re- 
quired to reduce interference from visible light 
sources. Circuit is sensitive enough to pick up 
hydrogen flames that emit no visible light. Ar- 
ticle describes operation of circuit and gives de- 
sign equations. Output can go directly to input 
port of microprocessor. — A. Ames, This Flame 
Detector Interfaces Directly to a jaP. £ ON Mag- 
azine. Oct. 20, 1976, p 122 and 124. 



SERIES- 
CONNECTED 
CHAMBER^ 




»5uA 



SMOKE DETECTOR — Battery-operated ioniza- 
tion-type smoke detector uses RCA CA3130 
opamp as interface for ionization chamber that 
provides picoampere currents. With opamp in 
pulsed mode (on for 20 ms of 20-s period), IC 
draws only 0.6 uA average instead of 600 /*A. 
Other active components and zener, all on RCA 



CA3097 array, provide low-battery monitor and 
horn-driver functions. When chamber detects 
smoke, combination of R F and D1 provides suf- 
ficient base current to keep Q3 and 04 on. 
Opamp is then powered continuously, and 
steering diode Z1 supplies continuous current 



to gate of Q2 for energizing horn. Battery drain 
is only 5 mA in monitoring mode. — G. J. Gran- 
ieri, Bipolar-MOS and Bipolar ICs Building 
Blocks for Smoke-Detector Circuits, IEEE Trans- 
actions on Consumer Electronics, Nov. 1977, p 
522-527. 



FIRE ALARM CIRCUITS 



341 




GAS/SMOKE DETECTOR WITH LATCH— CMOS 
latching logic provides 2-min time delay to pre- 
vent false alarm when power is first applied to 
fire alarm using Taguchi TGS308 gas sensor 
whose conductivity increases in presence of 



combustible gases. Normal voltage of 3 VRMS 
across R4 increases to about 20 V in presence 
of fire. Half of 12.6- V center-tapped transformer 
secondary is used for 6-V supply and full 12.6 V 
for DC horn supply. Latch is reset manually with 



Horn 12 Vdc 
Delta 16003159 
60 mA, 85/90 dB 
Mallory SC628 
6 mA, 70 dB 



SI to turn off alarm after gas level drops. Op- 
tional circuit shown can be used for automatic 
reset.— A. Pshaenich, "Solid State Gas/Smoke 
Detector Systems," Motorola, Phoenix, AZ, 
1975, AN-735,pS. 



Low Battery Circuit 




IONIZATION ALARM— Gates in Motorola 
MC14572 CMOS IC form two alarm oscillators, 
one energized in presence of smoke at ioniza- 
tion chamber and other for low battery. 
Standby currents of circuits are low enough to 
give at least 1 year of operation from 750- mAh 



battery. R6 is adjusted to give desired smoke 
detection sensitivity. Gates 1 and 2 form MVBR 
that drives horn at astable rate of 2.5 s on and 
0.2 s off in presence of smoke. When battery is 
low, comparator Q4-D2-D3 trips (about 10.5 V) 
and energizes inverter 4 of low-battery astable 



H: Delta Vdc 
16002933 



MVBR. DC horn is then powered at astable rate 
of about 1 s every 23 s to give early warning of 
need to change battery.— A. Pshaenich, "Solid 
State Gas/Smoke Detector Systems," Moto- 
rola, Phoenix, AZ. 1975, AN-735, p 7. 



342 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




3.9 V, 1/2W 



>100 k 

< R3 

y^ Sensitivity Control 



0.1 (iF 



V D D~ 



Horn: 24 vac 




6 V SS 
-15 V 



GAS/SMOKE DETECTOR WITH BEEPING alarms, CMOS astable MVBR using gates 3 and from 24-V winding of power transformer.— A. 

HORN— Taguchi TGS308 gas sensor increases 4 is energized to fire triac and drive AC horn to Pshaenich, "Solid State Gas/Smoke Detector 

voltage across R3 when sensor conductivity is give distinctive repetitive sound lasting about Systems," Motorola, Phoenix, AZ, 1975, AN- 

increased by combustible gases. After time 2.5 s, with 0.2-s intervals between beeps. Triac 735, p 6. 

delay provided to prevent power turn-on false gate drivers operate from -15 V supply derived 



CHAPTER 30 

Flasher Circuits 



Provide fixed or variable flash rates for LEDs, incandescent lamps, or 
fluorescent lamps used as indicators, alarms, warnings, and for such special 
effects as Christmas-light shimmer. See also Game and Lamp Control 
chapters. 




SEQUENTIAL AC FLASHER— Uses simple ring 
counter in which triac gates form part of 
counter load. Incandescent lamps come on in 
sequence, with only one lamp normally on at a 



time. Pulse rate for switching lamp can be ad- 
justed from about 1 every 0.1 s to 1 every 8 s. 
Circuit enclosed in dashed rectangle can be 
added to keep previous lamps on when next 



lamp is turned on. Only three stages are shown, 
but any number of additional stages can be 
added.— "Circuit Applications for the Triac," 
Motorola, Phoenix, AZ, 1971, AN-466, p 11. 



343 



344 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




3.9k 



VARIABLE FLASHER FOR LED— Terminal con- 
nections of National LM3909 flasher IC give 
choice of three different flash rates for LED used 
as indicator in battery portable equipment. Ex- 
ternal resistors provide additional adjustments 
of flash rate. Appropriate connections to pins 1 
and 8 make flash-controlling internal resistance 
3K. 6K, or 9K. Flasher operates at any supply 
voltage above 2 V, with low duty cycle to give 
long battery life.— P. Lefferts, Power-Miser 
Flasher IC Has Many Novel Applications, EDN 
Magazine, March 20, 1976, p 59-66. 



SHIMMER FOR CHRISTMAS LIGHTS— Circuit 
uses half of AC cycle to power lights conven- 
tionally. On other half-cycle, C charges and 
builds up voltage on gate of SCR. When firing 
point is reached, SCR conducts and allows re- 
mainder of this half-cycle to pass through light 
string. Result is flash that gives shimmer or 
strobe effect. C is 100-p.F 50-V electrolytic, R1 is 
2.7K, R2 is 22K, R3 is 3.3K, R4 is 100K pot, and 
RS is IK. Diodes are Motorola HEP R00S3. SCR 
is 6E C106B1 or Motorola HEP R1221 mounted 
on heatslnk.— R. F. Graf and G. J. Whalen, Add 
Shimmer to Your Christmas Lights, Popular 
Science, Dec. 1973, p 124. 




R2 Q 

20M 

■wv 



: t4 h KJ pH"iJ 



7.5M S I 



'-< 



>-^rW-<> 



< 



l-AV\r-i> 



MM74C908. MM74C918 



R3 
240k 



T 



2.2 ^F 



r 




DRIVING LED ARRAY— National MM74C908J 
MM74C918 dual CMOS driver has sections con- 
nected as Schmrtt-trigger oscillator, with R1 
and R2 used to generate hysteresis. R3 and C 



are inverting feedback timing elements, and R4 
is pulldown load for first driver. Output current 
drive capability is greater than 250 mA, making 



circuit suitable for driving array of LEDs or 
lamps.— "CMOS Databook," National Semi- 
conductor, Santa Clara, CA, 1977, p 5-38-5-49. 



FLASHER CIRCUITS 



34S 




»+5V 
■GNO 



1-Hz LAMP BLINKER— Single CMOS flip-flop 
generates approximately constant low-fre- 
quency signal from variable high-frequency sig- 
nal. RC network in feedback loop determines 
output frequency, which is Independent of rate 
at which flip-flop Is clocked if output frequency 
Is lower then dock frequency. If clock frequency 
Is lower, output transitions occur at half of clock 
frequency. Provides two outputs, approxi- 
mately equel in duty cycle but opposite In 
phase. Circuit was developed to blink lamp at 
1 Hz to Indicate presence of active digital signal 
having variable duty cycle in range of 100 to 
3000 Hz.— V. L Schuck, Generate a Constant 
Frequency Cheaply, EON Magazine, Aug. 20, 
1975, p 80 and 82. 



OFF 



3-V STROBE— Flash rate of 1767 lamp can be 
adjusted from no flashes to continuously on, in 
circuit using National LM3909 flasher IC with 
external NPN power transistor rated at 1 A or 
higher. Can be used as variable-rate warning 
light, for advertising, or for special effects. With 
lamp in large reflector in dark room, flashes sev- 
eral times per second are almost fast enough to 
stop motion of dancer. — P. Lefferts, Power- 
Miser Flasher IC Has Many Novel Applications, 
EDN Magazine, March 20, 1976, p 59-66. 




Z0M 

— Wr 



V CC -5V 

O 



| 



tfFD ff^FC 




OUT-OF-PHASE DOUBLE FLASHER— Sections 
of National MM74C908/MM74C918 dual CMOS 
driver are connected as Schmftt-trigger oscil- 
lator, with LEDs at output of each section so 
LEDs will flash 180° out of phase. High output 
current capability makes circuit suitable for 
driving two LED arrays.— "CMOS Databook," 
National Semiconductor, Santa Clara, CA, 1977, 
p 5-38-5-49. 



346 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



TO +9Vo 



TO -9 V o 



TO Cl» 




CLOCK DRIVE FOR FLIP-FLOP FLASHER— 555 
timer connected as astable MVBR generates se- 
ries of timing pulses at rate determined by value 
of capacitor and setting of 1-megohm pot. Pro- 
vides automatic string of input pulses for driv- 
ing flip-flop of dual flasher. Pulse output goes to 
Input capacitor CI of flip-flop.— F. M. Mims, "In- 
tegrated Circuit Projects, Vol. 5." Radio Shack, 
Fort Worth, TX, 1977, 2nd Ed., p 30-37. 



SEQUENTIAL SWITCHING OF LOADS— Ring 
counter using four-layer diodes D N provides se- 
quential switching of loads under control of 
input pulse-train signal. Indicator lamps are 
shown, but any load from 15 to 200 mA can be 
switched. After power is applied, reset switch 
must be pressed to establish current through L. 
When switch is released, this current flows 
through C 2 and breaks down D 2 , allowing cur- 
rent to flow through first lamp I,. Input pulse to 
transistor Q (normally held off by current 
through R,) turns Q off and removes power from 
diode circuits, thus turning I, and D : off. At end 
of input pulse, Q comas on and restores power 
to diode circuits, but all loads will be turned off. 
Voltage on C 3 now adds to 6 V normally across 
0„ making D 4 break down and turn on I,. Next 
input pulse will break down D e in same manner . 
Output signals may be picked up as negative 
pulses at A or B or by current-sensing at C if re- 
quired for controlling larger loads. — J. Bliss and 
D. Zlnder, "4-Layer and Current-Limlter Diodes 
Reduce Circuit Cost and Complexity," Moto- 
rola, Phoenix. AZ. 1974, AN-221. p 5. 




Q = 2N4400 




1-Hz AUTO FLASHER— Lamp drawing nominal 
600 mA is flashed at 1 Hz by National LM3909 
flasher IC operating from 12-V automotive bat- 
tery. Use of 3300-pF capacitor makes flasher IC 
immune to supply spikes and provides means 
of limiting IC supply voltage to about 7 V.— P. 
Lefferts, Power-Miser Flasher IC Has Many 
Novel Applications, EON Magazine, March 20, 
1976, p 59-66. 



FLASHEB CIRCUITS 



347 



»v? 




DEMONSTRATION FLIP-FLOP— Two sections 
of LM3900 quad opamp form bistable MVBR for 
flip-flop having two stable states. When input 
is grounded momentarily, output of one of 
opamps swings completely on and turns other 
opamp off. LED indicates which opamp is on at 
any particular time. Next grounding of input re- 
verses conditions. Ideal for classroom demon- 
strations. — F. M. Mims, "Integrated Circuit Proj- 
ects, Vol. 5," Radio Shack, Fort Worth, TX, 1977, 
2nd Ed., p 30-37. 



SCR FLASHES LED— UJT oscillator Q1 provides 
timing pulses for triggering SCR driving red 
Radio Shack 276-041 LED. Circuit draws only 2 
mA from 9-V battery when producing 12 flashes 
per second. SCR is 6-A 50-V 276-1089.— F. M. 
Mims, "Semiconductor Projects, Vol. 2," Radio 
Shack, Fort Worth, TX, 1976, p 78-84. 




NSLS0S7 




47 a 



— _3V 



SINGLE-FLASH LED— Mono MVBR connection 
of National LM3909 IC produces 0.5-s flash with 
LED each time pushbutton makes momentary 
contact. — "Linear Applications, Vol. 2," Na- 
tional Semiconductor, Santa Clara, CA, 1976, 
AN-154, p 9. 



348 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



300'.! 
VDC "^ vvv 




ALTERNATING RED/GREEN— National LM3909 
IC Is connected as relaxation oscillator for flash- 
ing red and green LEDs alternately. With 12- 
VDC supply, repetition rate Is about 2.5 Hz. 
Green LED should have Its anode or positive 
lead toward pin 5 as shown for lower LED, 
where shorter but higher-voltage pulse Is avail- 
able. LED types are not critical.— "Linear Appli- 
cations, Vol. 2," National Semiconductor, Santa 
Clara, CA, 1976, AN-154, p 3. 



ALARM-DRIVEN FLASHER— Simple two-tran- 
sistor flasher circuit for annunciator system is 
activated by alarm. Operator acknowledges 
alarm condition by depressing Sa, which 
changes lamp from flashing to steady ON con- 
dition. 6-V incandescent lamp draws about 0.3 
A through Q 2 , but IK load resistor for Q, limits 
current of this transistor to about 6 mA so 
smaller transistor can be used. — T. Stehney, 
Flasher Design Cuts Extra Components, EON 
Magazine, Sept. 20, 1978, p 144. 





// 



osc. 

LM3909N 



tf 



3QOjuF 
3V 



FOR 3V SUPPLY 
LEAVE PIN 1 
OPEN 



FLASHING LED IS REMOTE MONITOR— Circuit 
uses National LM3909 flasher ICto drive LEDfor 
monitoring remotely located high-voltage 
power supply. When 43K dropping resistor is 
located at power supply, all other voltages on 



the line, IC, and LED will be less than 7 V above 
ground, for safe remote monitoring, Use any 
LED drawing less than 150 mA.— P. Lefferts, 
Power-Miser Flasher IC Has Many Novel Appli- 
cations, BDN Magazine. March 20, 1976, p 59- 
66. 



1.5-V OR 3-V INDICATOR— Digi-Key LM3909N 
flasher/oscillator drives LED serving as ON/OFF 
indicator for battery-operated devices. At flash 
rate of 2 Hz, battery life almost equals shelf 
life. — C. Shaw, ON-OFF Indicator for Battery 
Device, QST, March 1978, p 41-42. 



FLASHER CIRCUITS 



349 








SCRl 
(FRONT) ' 


k 

C A G 


tL 


-±r 




FLIP-FLOP DRIVES SCR— UJT relaxation oscil- 
lator Q1 serves as clock for driving section of 
7473 dual flip-flop. One output of flip-flop 
flashes Radio Shack 276-041 red LED to indicate 
operating status. Other output alternately trig- 
gers SCR which can be 6-A 50-V 276-1089, for 



flashing lamp load. Load and SCR supply volt- 
age depend on application but must be within 
SCR rating. — F. M. Mims, "Semiconductor Proj- 
ects, Vol. 2," Radio Shack, Fort Worth, TX, 1976, 
p 62-70. 




LED BLINKER— Two sections of SN7400 quad 
gate form MVBR operating at low enough fre- 
quency so LED status indicators come on and 
off slowly for visual observation of MVBR. LEDs 
are optional and do not affect operation of 
MVBR. Capacitors must be same value. Ideal for 
student demonstration in classroom or as Sci- 
ence Fair exhibit.— A. MacLean, How Do You 
Use ICs?, 73 Magazine, Dec. 1977, p 56-59. 



RED/GREEN LED FLASHER— One section of 
LM324 quad opamp is connected as square- 
wave generator giving about 1 flash per second 
for each LED. Series resistors for LEDs have dif- 
ferent values because they have different for- 
ward voltage requirements. If LED 2 glows be- 
tween flashes, increase value of R6 slightly. Too 
large a value for R6 reduces flash brilliance of 
LED 2. Supply can be 5 or 6 V.— F. M. Mims, 
"Semiconductor Projects, Vol. 1," Radio Shack, 
Fort Worth, TX, 1975, p 69-74. 



R2>100K 



Bl ;=;6 VOLTS 



Rl 
-A/VV — 

10 MO 




R4>100K 



R3 
100 K 



LE01 @ 



) (GREEN! 



7 6 5 4 3 2 1 

n n n n n n n 



Ki< 100 



?7O-300 
(SEE TEXT) 



LED 2 M MIRED! 



ICKTOPI 



U U U LJ U U U 

8 9 10 11 12 13 14 



o 



LED (BOTTOM! 

NOTE; SOME LEDs MAY 

HAVE DIFFERENT PIN OUTLINE 



B1-5-9V 




COMPARATOR LED FLASHER— One section of 
LM339 quad comparator drives two RS2016 
NPN transistors having LED load, to give simple 
flasher for classroom demonstrations. Circuit 
can be duplicated with other three sections to 
give four flashers. Connecting R2 to pin 1 of IC 



gives conventional ON/OFF flash cycle in which 
LED turns on and off rapidly. Connecting R2 to 
pin 6 makes LED turn on rapidly and turn off 
very slowly. C1 controls flash interval; typical 
value is 0.01 f*F.— F. M. Mims, "Integrated Cir- 
cuit Projects, Vol. 5," Radio Shack, Fort Worth, 
TX, 1977, 2nd Ed., p 45-51. 




CAR BATTERY 



12-V FLUORESCENT— Relay acts as mechanical 
DC/AC converter operating off 12-V car battery. 
Each time relay opens, inductive kick in relay 
coil is stepped up by output transformer to high 
enough voltage for ionizing 24-inch fluorescent 
tube, giving flash that can serve as emergency 
flasher when car breaks down. — Circuits, 73 
Magazine, June 1975, p 175. 



350 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




1.5-V LED FLASHER— National LM3909 IC op- sets flash rate at about 1 Hz.— "Linear Appli- 

erating from 1 .5-V battery drives NSL5027 LED cations. Vol. 2," National Semiconductor, Santa 

in such a way that current is drawn by LED only Clara, CA, 1976, AN-154, p 2. 
about 1% of time. External 300-/uF capacitor 




2-kHz FLASHER FOR LED— Single 1 .5-V cell pro- 
vides power for National LM3909flasher IC that 
operates at high enough frequency to appear on 
continuously, for use as indicator in battery 
portable equipment. Duty cycle and frequency 
of current pulses to LED are increased by chang- 



ing external resistors until average energy 
reaching LED provides sufficient light for appli- 
cation. At 2 kHz, no flicker is noticeable.— P. Lef- 
ferts, Power-Miser Flasher IC Has Many Novel 
Applications, EDN Magazine, March 20, 1976, p 
59-66. 



Silicon 
Solar cell 



1 



Silicon 
Solai cell 



Silicon 
Solar cell 



NiCd 
1.25v. 



1N34 



J7 



-&■ 







LED 




^V 




1 8 7 6 5 

S LM3909 

i 1 2 3 4 




i — L*J J> 



Silicon 
Solar cell 



1 30b>f 

LED FLASHER— Requires only LM3909 IC and 
external capacitor operating from 1.26-V nicad 
or other pen light cell. Circuit can be duplicated 
for as many additional flashing LEDs as are de- 
sired for display. Optional charging circuit uses 
silicon solar cells and diode for daytime charg- 
ing of battery automatically. — J. A. Sandler, 1 1 
Projects under $11, Modern Electronics, June 
1978, p 54-58. 



^ FOR HIGH VOLTAGE 

^ | ^NSL5Q27 



osc. 

LM3909N 




6-V OR 15-V INDICATOR— Uses Digi-Key 
LM3909N flasher/oscillator to drive LED at 2 Hz 
as ON/OFF indicator for battery-operated de- 
vices. For 6-V battery, C T is 400 /*F, R s is 1000 
ohms, and R FB is 1500 ohms. For 15 V, corre- 
sponding values are 180, 3900, and 1000. Bat- 
tery life is essentially same as shelf life. — C. 
Shaw, ON-OFF Indicator for Battery Device, 
QS7", March 1978, p 41-42. 



FAST 1.5-V BLINKER— Addition of 1K resistor 
between pins 4 and 8 of National LM3909 IC in- 
creases flash rate to about 3 times that obtain- 
able when 300 pF is connected between pins 1 
and 2. Modification of external connections 
gives choice of 3K, 6K, or 9K for internal RC re- 
sistors. — "Linear Applications, Vol. 2," National 
Semiconductor, Santa Clara, CA, 1976, AN-154, 
P2. 



FLASHER CIRCUITS 



351 




1-A LAMP FLASHER— National LM195 power 
transistor is turned on and off once per second 
for flashing 12-V lamp. Current limiting in 
LM195 prevents high peak currents during turn- 
on even though cold lamp can draw 8 times nor- 
mal operating current. Current-limiting feature 
prolongs lamp life in flashing applications.— R. 
Dobkin, "Fast IC Power Transistor with Thermal 
Protection," National Semiconductor, Santa 
Clara. CA, 1974, AN-110, p 5. 



POWER 
SWITCH 



<r<3^C 



o-r 



-o=d- 



HEPR01701 



>R2 



CRi R< 

♦I VW-+ 



HEPRO170 < M 



H7VAC LINE 




POWER 
SUPPLY 



BLOWN-FUSE BLINKER— Neon .lamp NE-2 
glows steadily when fuse is good and flashes 
when fuse opens. Flash rate, determined by R1 
and CI, is about 10 flashes per second for values 
shown. — T. Lincoln, A "Smart" Blown-Fuse In- 
dicator, QST, March 1977, p 48. 



\ 276-2009 



<15.000O 



10 MF 




bi:=:6v 



AUTO-BREAKDOWN FLASHER— Two-transis- 
tor amplifer with regenerative feedback sends 
60-ms pulses of currents up to several amperes 
through low-voltage lamp to give high-bril- 
liance flashes without destroying lamp. L1 can 
be PR-2 lamp (Radio Shack 272-1120).— F. M. 
Mims, 'Transistor Projects, Vol. 1," Radio 
Shade, Fort Worth, TX, 1977, 2nd Ed., p 27-32. 



CHAPTER 31 

Frequency Counter Circuits 



Used to indicate frequency value directly on digital display by counting 
number of cycles in period of exactly 1 second. Included are preamps, time 
bases, and prescalers for extending counting range to as high as 500 MHz. 




4-MHz COUNTER — Portable frequency counter to minimize battery drain. One multiplexed out- 



using RCA CMOS logic draws only 300 mW (12 
V at 25 mA) yet operates to well above 4 MHz. 
Supply voltage can be between 4 and 15 V, 



put is for three least significant figures and 
other for four most significant figures. Article 
describes operation in detail. Applications in- 



loosely regulated, without affecting accuracy, elude setting RTTY mark and space tones, FM 
Display uses multiplexing with 10% duty cycle 



repeater tones, signal-generator frequencies for 
TV alignment, tuning musical instruments, and 
serving as tachometer or speedometer in car. — 
R. M. Mendelson, Milliwatt Portable Counter, 
Ham Radio, Feb. 1977, p 22-25. 



352 



FREQUENCY COUNTER CIRCUITS 



353 



FN0-S03 COMMON CATHODE DISPLAYS 



1.2 Mn 




'INPUT 

.1 

toov 



^T^-r&t 





DBK ! 

O— vWHl-f- 



f*-C■UT 



^■5V♦ VW— ► 



0-3 MHz PREAMP— Provides wide frequency 
response required for amplifying 100 mV P-P 
input signals to 5-V level for driving CMOS logic 
of frequency counter. — R. Tenny, Counter Pre- 
Amp Matches CMOS Logic Capability, EDN 
Magazine, Sept. 20, 1976, p 1 14 and 1 16. 



50 MHz WITH 1-Hz RESOLUTION— Combina- 
tion of CMOS and TTL devices reduces chip 
count for digital frequency counter that pro- 
vides 1-Hz resolution from below 20 Hz to above 
50 MHz. Use of 10:1 prescaler, also given in ar- 
ticle, extends range to above 300 MHz with 10- 
Hz resolution. Uses Intersil 7208 CMOS seven- 
decade counter that includes multiplexer, 
decoder, drivers, and other controls for Fairchild 
FND-503 8-dlgit display. High-stability 5.24288- 
MHz crystal oscillator and frequency divider 
provide 1-s gate required for counting, outputs 
for synchronizing multiplexer, and short pulses 
for latching and resetting counters. Resolution 
can be decreased by factor of 10 by connecting 
pin 1 1 of 7207A to V co , which is regulated 5 V.— 
H. E. Harris, Simplifying the Digital Frequency 
Counter, Ham Radio, Feb. 1978, p 22-25. 



m 





T. 






Uf 
THRU 

ue 

SN744I 


19 




8 




• 




13 


n n 6 


"* 






C O-L 


10 ° 






oo-i 


' 




16 c 







T 



THUMBWHEEL 
SWITCHES 



2N390518) 





PRESET-FREQUENCY ALARM— When selected 
frequency occurs in Nixie-driving counter, 
alarm circuit triggers and locks until reset man- 
ually. Requires one SN7441 Nixie decoder/ 
driver, one decimal-type thumbwheel switch, 
and one 2N3905 transistor for each digit of dis- 



play in counter. Four connections are made to 
each counter stage to get BCD inputs A, B, C, 
and D for 7441. Connections can be made to 
7475 quad latch in typical counter. Circuits are 
for 8-digit display. When display reaches digit 
to which switch is set, switch output is 



, o TO ALARM 

CIRCUIT 
' " (YOUR CHOICE) 

NORMALLY CLOSED 
PUSHBUTTON 



grounded. When all switch outputs are 
grounded, all transistors are turned on and SCR 
fires to actuate alarm relay. If latching is unde- 
sirable, use medium-power NPN transistor in 
place of SCR. — W. L. MacDowell, Frequency De- 
tectorfor Your Counter, 73 Magazine, Oct. 1976 
p 50-51. 



354 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



no-sos cannon cathocc wspla/s 



.IS .01 s 





TIME BASE— Intersil 7207 IC generates clock 
and housekeeping pulses required for fre- 
quency counter. With pin 11 grounded, gate 
output is high for 0.1 s and low for 0.1 s. With 
pin 11 high, gate is high 0.01 s and low 0.01 s. 
1.6-kHz square wave at pin 12 is useful for mul- 
tiplexing displays. Update output is narrow 
negative-going pulse coincident with rising 
edge of gate output, for use in transferring 
count to display latches. Reset output is used to 
reset counter. — D. Lancaster, "CMOS Cook- 
book," Howard W. Sams, Indianapolis, IN, 1977, 
p161. 



./ 

200Y 



' ■ i» 1 



rn 



30 MHz WITH 10-Hz RESOLUTION— Simplified 
counter design using low chip count provides 
multiplexing of seven digits in Fairchild display, 
for applications where 1-Hz resolution is not 
needed. 7207 oscillator/timer gives counting in- 
terval of 0.1 s, for updating display 5 times per 
second. Article also gives circuit of 10:1 pre- 
scaler that increases frequency limit to 300 
MHz, though with 100-Hz resolution. Total 
counter current drain is 300 mA from regulated 
S-V supply. — H. E. Harris, Simplifying the Digital 
Frequency Counter, Ham Radio, Feb. 1978, p 
22-25. 




w 



60-kHz WWVB PREAMP— Installed in loop an- 
tenna to boost strength of 60-kHz standard-fre- 
quency broadcasts from RIBS station at Boul- 
der, Colorado, enough to drive digital frequency 
counter for which circuit i» also given in article. 



Although construction details apply to double- 
copper shielded 54-inch-diameter circular loop, 
preamp can also be used with simple un- 
shielded wood-frame loop. Output coax sup- 



plies regulated 10 VDC for preamp. Article in- 
cludes techniques for minimizing interference 
from nearby TV receivers. — H. Isenring, WWVB 
Sig nal Processor, Ham Radio, March 1 976, p 28- 
34. 



FREQUENCY COUNTER CIRCUITS 



355 



5-MHz FRONT END— Used ahead of 5-MHz fre- 
quency counter to make input signal swing 
from logic of V to logic 1 of about 10 V as 
required for accurate counting of frequency for 
input signal having any input waveform shape 
and level. Input of front end has high impedance 
to minimize effect on input waveform. FET tran- 
sistor Q1 and bipolar buffer 02 drive Schmitt 
trigger using half of Motorola MC75108 dual line 
receiver. — D. Aldridge, "Battery-Powered 5- 
MHz Frequency Counter," Motorola, Phoenix, 
AZ, 1974, AN-717, p 5. 



V A 



R5 
1 Meg 



1 




Ql - 2N5716 
Q2 - 2N4403 
Q3 — 2N4403 
Q4 - MPS 918 
Zl - 1N5236 



f \ M . H * 1MHZEXTJ fTIMEBASt 

osc W I 



I 

^ 20M , 



100kHz 



-s'd! 



J)-64pF 



Y.MC14518 
R 



1 



10kH2 



C 
V4MC14518 

HE, 



t 



1 kHz 



C 
%MC14518 



I 



100 Hz 



%MC14518 



I "z" II R "z u i II R °z Q i II R °z Q i 1 



I 



10 Hz 



'/.MC14518 



I 



1Hz 



C 
%MC14518 

h 0. oft. 



'AMC14518 



NPUT 
FROM 
SIGNAL" 
CONDI- 
TIONER 



R 
'/.MC 14518 



MC14511 




E * r " ' ■ e n r e n i ■ ■ e n r En 

Q p QlQ;Q 3 0qQ,Q;Q 3 Q0O1O2O3 I O11Q1O2Q3 0.0 



MC14511 



MC14511 



w ■•-»ii i »»ii 



COUNTER LATCHES, DECODERS, DISPLAYS 

12-V 5-MHz COUNTER— Portable counter is de- 
signed with low-power logic to minimize bat- 
tery drain, yet provides good performance. 
Since most of milliwatt power drain is taken by 
digital readout, circuit blanks out LED display 
when there is no input signal. Time base divides 
1-MHz crystal oscillator frequency down to de- 



sired enable time, up to 10s, using 3% MC14518 
dual decade counters connected in ripple- 
through mode. Actual counting of input signal 
codes is also done with MC14518 counters. 
Latches and BCD to 7-segment decoders use 
MC14511s. Enable line turns first counter on 
and off for precise enable time period. Strobe 



line transfers count into memory of MC14511 
latch decoder, and control line resets MC14518 
decade counters for next count cycle. Displays 
are Monsanto M AN-4 LEDs. Article traces circuit 
operation in detail and gives timing diagram.— 
D. Aldridge, CMOS Counter Circuitry Slashes 
Battery Power Requirements, EDN Magazine, 
Oct. 20, 1974, p 65-71. 



356 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



300-MHz PRESCALER— Uses Fairchild 9SH90 IC 
to divide input signal frequency by factor of 10 
up to 320 MHz. Full-wave diode llmfter at input 
prevents damage to IC. R 4 is chosen to bias IC 
at point of maximum sensitivity; typical value 
is 680 ohms. Transistor amplifier provides 2-3 
V P-P output. Bias resistor R B is set to make col- 
lector-base voltage 3 V; typical value is 620 
ohms. Wind one lead of 4.7-/ttH choke around 
nail 4 times, then remove nail and slip ferrlte 
bead over end of wire before connecting It to 
pin 1. Keep all leads as short as possible. Article 
covers construction and alignment in detail. — 
I. Math, Math's Notes, CO. May 1975. p 42-44 
and 64. 




r MO- S03 COHMOH CATHOOt D/SPLAYS 




CA3130 >-• ►TO TRIGGER 




DIRECT-COUPLED PREAMP— Provides fre- 
quency response from to 1 MHz at very low 
power levels, as required for driving CMOS logic 
of frequency counter. Diodes protect input from 
overload. Output impedance of frequency 
source should be kept below SOK to minimize 
noise pickup. — R. Tenny, Counter Pre-Amp 
Matches CMOS Logic Capability, EDN Maga- 
zine, Sept. 20, 1976, p 114 and 116. 



"INPUT I 
J 

too V 



..^ ink l O cc i ^"" la — 



"4 ^^° cc y oo \ ' 





270 

INPUT O \C- 



6 MHz WITH 10-Hz RESOLUTION— Intersil 7208 
CMOS counter provides multiplexing of six dig- 
its in Fairchild display operating from 5-V reg- 
ulated supply. Uses MOSFET 4673 input 



stage. — H. E. Harris, Simplifying the Digital Fre- 
quency Counter, Ham Radio, Feb. 1978, p 22- 
25. 



1.5-GHz PRESCALER— Motorola MC1697 IC 
provides division by 4 to extend operating 
range of 400-MHz counter above 1.5 GHz. Cir- 
cuit will operate on input signals as low as 1 
mW. Requires 60-mA power supply at -7 V. 
Article gives construction and test details. — J. 
Hinshaw, 1.5 GHz Divide-by-Four Prescaler, 
Ham Radio, Dec. 1978, p 84-86. 



FREQUENCY COUNTER CIRCUITS 



357 



Input 




110v.a.c. 



TWO-DECADE SCALER— Solid-state frequency 
scaler extends range of older frequency 
counters by factors of 10 and 100, or up to 10 
MHz for 100-kHz counter. Emitter-follower Q, 
provides matching from high input impedance 
to low impedance for driving sensitive clipper 
Q 2 that operates class B and presents 4 V P-P 
square wave to decade counter. Input accepts 
1 to 14 V P-P.— D. Peck, A Solid State Scaler for 
Frequency Counters, CO, April 1974, p 24-27. 



200-MHz BUFFER— Developed for use ahead of 
prescaler in 200-MHz autoranging frequency 
counter. Provides high input impedance to 
count-sensing device. Circuit includes Schmitt 
trigger action. Sensitivity is about 50 mV P-P. — 
T. Balph, "A 200 MHz Autoranging MECL— 
McMOS Frequency Counter," Motorola, Phoe- 
nix, AZ, 1975, AN-742, p 10. 



-*- 



68 pF 

33 k 
II V\rV- 



"a 



MMT3823 



-5 V — VW #- 



;feo.oi MF "p ' 



-0+5 V 



MMT2857 



!00MH!(T\ 



510 | 
/ VS* ♦ 

20^F *T> 

i * — q ^c — *■ 

15|iF > 



1/3 MC10216 



0.1 mf 
-7F 



F 2 



I — — "*t~T 



0.1 »iF -5 V 



TL 




-5 V-VW > >+tV— *■ 



< J««OOj«i-i Qj 7 4H00Wi-O 




O +9V 



IMPROVED PREAMP— Replaces inefficient 
input circuit of inexpensive frequency counter, 
to ensure accurate counting from DC to over 60 
MHz. Circuit brings input signal waveform to 
TTL level of 3.5 V P-P while providing required 
perfect square waves down to lowest-fre- 
quency input signal. Input circuit is balanced 



FET source-follower having extremely high 
input impedance. Back-to-back diodes provide 
overload protection. Input stage drives 733 dif- 
ferential video amplifier having 100-MHz band- 
width and gain of 400. 2N709 switching transis- 
tor squares preamp signal for TTL translator 



■O-s.sv 



using two sections of 74H00 high-speed quad 
NAND gate. Circuit requires dual-polarity sup- 
ply delivering at least 63 mA; regulation is op- 
tional. — G. Beltrami, High-Impedance Preamp 
and Pulse Shaper for Frequency Counters, Ham 
Radio, Feb. 1978, p 47-49. 



358 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



25-250 MHz PRESCALER— Based on use of 
Fairchild 95H90 decade counter, with preamp 
Q1 and associated components selected for 25- 
250 MHz range. 1N914N diodes prevent over- 
loading of input. Voltage regulator is LM340T-5. 
LI is 8 turns No. 28 wound on body of 1 000-ohm 
or larger VW resistor, with ends soldered to re- 
sistor leads. Quarter-wave whip antenna at 
input will pick up adequate signal from 1-W 146- 
MHz transceiver hand-held 6-10 feet away. 
Counter provides division by 10. — R. D. Shriner, 
Prescaler Updates the DVM/Frequency Counter, 
QST, Sept. 1978, p 22-24 and 37. 



+ 22V 
SECTION OF SCALER 
SWITCH 



(^ 




U2 
REGULATOR 




0.01>jF 



U1 

95H90 

PRESCALER 



¥* 



XNOTE: PINS 2,6.7.10.(1,12.13, 
14 AND 15 ARE COM. 



I 
t 

CI2 



ai 
e/2 



■-.or 




60 kHz 
2.5V P-P. 



V P-Pl\ ABV P-Pt — i 



ZERO CROSSING 
DETECTOR ' 







7490 

H-/0 



-cr 



J0Hz_J\ 
O V.S 

100 Hz „ O— 



TT - 



"TT" 



7490 

H-/0 



kHzJ) 
10 kHz] 



TT 



i ED- 



4> 



~% 




rh iooo 



_C29 4 
^SOOjif 
50* 



TT 

U2 



R20 

— wv 

75 
SW 
.C3S 
*500i>F 
35V 



r 



LINE 
DRIVER 






I 



T 



_C33 

35V 



X 



COUNTER DRIVE FOR WWVB— Uses LM31 1 as 
true zero-crossing detector for 60-kHz carrier of 
NBS standard-frequency station at Boulder, 
Colorado. Resulting square wave is fed to chain 
of 7490 dividers whose outputs are selected by 



S2 to serve as gate for frequency counter. T1 is 
24-V 500-mA power transformer, and T2 is 40- 
kHz cup-core slug-tuned RF transformer as used 
in many TV remote controls. Primary induc- 
tance {7.5-46 mHI of T2 is tapped at 0.5 mH; 



secondary is 20 /uH. Article also gives circuit of 
preamp that can be built into 60-kHz loop an- 
tenna to build up signal strength to 0.4 V as re- 
quired for input to processor. — H. Isenring, 
WWVB Signal Processor, Ham Radio, March 
1976, p 28-34. 



FREQUENCY COUNTER CIRCUITS 



359 



10:1 PRESCALER FOR 500 MHz— Uses Fairchild 
11C06 D flip-flop and Fairchild 95H91 divide-by- 
5 counter. Input sensitivity is less than 100 mV 
from 10 to 500 MHz. Back-to-back diodes pro- 
tect 11C06 input from overloads. Output is fed 
to 50-MHz frequency counter. Use regulated 
supply.— W. C. Ryder. 500-MHz Decade Pre- 
scaler. Ham Radio, June 1975, p 32-33. 



ne- 



< SI T(N9(4 ▼ IN9I4 



1 



T, 



- 150 pF 









A, 



nr 






1 




TO INPUT OF 
'NEXT COUNTER 



„COUNT * BB 

° ENABLE ° < " 

PULSE 



'13 OO _ _. . 

O— O(RESET) 

PULSE 



UPDATE TO 100 MHz— Simple counter stage 
can be added to input of existing frequency 
counter to extend direct counting range to 100 
MHz, preparing it for use with 1-GHz prescaier. 
Use 74S196 presettable decade counter and 
74S00 NAND-gate IC. If existing counter has 
positive reset pulse, connect C to CC and D to 
DD; if reset pulse is negative, connect C to D. If 
count enable pulse is negative, connect A to AA 
and B to BB; if positive, connect A to B. Power 
supply bypass capacitor should be shunted by 
47-^.F 10-V tantalum or electrolytic. Article cov- 
ers modifications required in some counter 
input stages.— I. MacFarlane, How to Modify 
Your Frequency Counter for Direct Counting to 
100 MHz, Ham Radio, Feb. 1978. p 26-29. 



INPUT 
FREQ. 



STROBE LINE 




MULTIPLEXED DISPLAY— Used with battery- 
operated frequency counter to reduce battery 
drain by multiplexing single decoder driver be- 
tween all of MAIM-4 displays. Readout is inte- 
grated by eye over total time period, making 



display appear continuous. Display operates at 
peak of 20 mA but duty cycle is only 12.5%. 
Counter is operated from 6-V supply. Four 
MC14021 8-bit shift registers implement multi- 
plexing and provide latches needed to store 



count from MC14518 counter chain. Article de- 
scribes operation in detail and gives circuit of 
companion front end and 5-MHz counter. — D. 
AldrkJge, CMOS Counter Circuitry Slashes Bat- 
tery Power Requirements, EDN Magazine, Oct. 
20, 1974, p 65-71. 



360 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



500 MHz WITH 100-Hz RESOLUTION— Circuit 
provides separate 0-50 MHz preamp Q1-Q7 and 
50-500 MHz prescaler for Intersil ICM7207A 7- 
digit CMOS frequency counter. 500-MHz pre- 
scaler uses Fairchild 11C90 that drives TTL di- 
rectly, with 2N5179 transistor as preamp. LI 
and output capacitance of 2N5179 form low-Q 
resonant circuit. U3 is 50-MHz prescaler for both 
preamps. Crystal frequency is 5.242880 MHz. 5- 
V regulators are MC7805, and 12-V regulator is 
MC7812. Article covers construction and ad- 
justment. — J. H. Bordelon, Simple Front-Ends 
for a 500-MHz Frequency Counter, Ham Radio, 
Feb. 1978, p 30-33. 




FREQUENCY COUNTER CIRCUITS 



361 



InT. MC10115 1MMC10115 1/4M ^ 10115 Prop Delay 




Reset [ / 



1/4 
MC10102 



510 



RAMP GENERATOR/COMPARATOR— Devel- 
oped for frequency counter using standard ECL 
components. One input to comparator is from 
integrator stage, and other is from ramp gen- 
erator driven by reset signal from UJT oscilla- 
tor. — W. R. Blood, Jr., "Measure Frequency and 
Propagation Delay with High Speed MECL Cir- 
cuits," Motorola, Phoenix, AZ, 1972, AN-586, 
P3. 



■ov EE 



INPUT BUFFER FOR 100-MHz COUNTER— Can 
be used with 500-ohm probe for wide range of 
high-frequency input signal levels and wave- 
forms, as part of frequency counter using stan- 
dard emitter-coupled logic. Opamps used have 
50-ohm input impedance. 450-ohm resistor in 
series with coax gives 10:1 attenuation factor 
(80 mV at amplifier input when measuring 800- 
mV ECL swing).— W. R. Blood, Jr., "Measure 
Frequency and Propagation Delay with High 
Speed MECL Circuits," Motorola, Phoenix, AZ 
1972, AN-586, p 3. 



Connector 
J-, 0.001 MF 



^_ 



'450 

To Point 
Under Test 




PREAMP OR 
BIAS NETWORK 



ONE TTL LOAD 




40:1 SCALER FOR 1200 MHz— Uses Fairchild 
11C05 dhride-by-4 counter and 95H90 decade 
divider. Unused CP input is tied to ground. Tran- 
sistor translates ECL level to TTL for driving one 
unit load. Operates from single regulated power 
supply. Input may be AC or DC coupled so either 
input amplifier or simple bias network (also 
given in article) may be used. 10K resistor from 
pin 4 to ground eliminates noise triggering in 
middle frequency ranges.— D. Schmieskors, 
1200-MHz Frequency Scalers, Ham Radio, Feb. 
1975, p 38-40. 



SCALER FOR CB — Low-cost prescaler for low- 
range frequency counter permits accurate mon- 
itoring of 450-MHz CB transceiver. Fairchild 
1 1C90 decade counter gives division by 10 for 
counters covering up to 45 MHz. For lower- 
range counter, add 74196 TTL decade counter 
as shown to give total division by 100 for con- 
version to 4.5-MHz output. D1 and D2 should be 
fast-switching diodes such as 1N914 or 1N4148. 
Keep input signal under 1 V to avoid damaging 
11C90. Will operate from 5-V supply or four D 
cells.— P. A. Stark, 500 MHz Scaler, 73 Maga- 
zine, Oct. 1976, p 62-63. 



♦6 V0C 




o Output 



362 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



10:1 SCALER — Used to increase range of fre- 
quency counter. Sensitivity is 20 mV at 175 
MHz, 40 mV at 220 MHz, and 90 mV at 250 MHz. 
Fairchild IC is used. Simple L-section filter at 
output rolls off frequencies above 30 MHz, al- 
lowing scaler to be used up to 250 MHz without 
erroneous counting of second or third harmon- 
ics of square-wave output of scaler if counter in 
use will respond to 60 MHz or more. — E. Guerri, 
Frequency Pre-Scaler, Ham Radio, Feb. 1973, p 
57. 




COMMON-CATHODE LED DISPLAY 



>+5V 
•IK 



XI 



;32pf 



6. 5536 -MHz -j- 
CRYSTAL -T- 



22 pF 





1 


M 


a 

,N 


M 


II 


II 


II 


1 


1 


l-l 


.M 


II 


11 


\\ 


\l 


1 



+ 5V 




GATE 
SELECT 

.01 SEC 
+ 5V 



>5V 



\^ 



+5V 



7208 

(INTERSIL) 

TOP VIEW 



»5V 



STORE 



INHIBIT 



RESET 



MULTIPLEX 



1 



1SEC 



COUNTER 



3130 (RCA) counter and display. Square wave is further di- 

vided to produce 0.1-s and 0.01 -s counting gates 
along with reset and update commands. RCA 
INPUT CONDITIONING 3130 opamp is used for conditioning of input 

10 Hz TO 2 MHz— Seven-decade Intersil 7208 ing waveform from 7207 IC which divides signal.— D. Lancaster, "CMOS Cookbook," 
latched and multiplexed frequency counter 6.5536-MHz crystal oscillator output by 2 ,a to Howard W.Sams, Indianapolis, IN, 1977, p 380- 
with direct digit and display drive obtains tim- produce 1600-Hz square wave for multiplexing 382. 



FREQUENCY COUNTER CIRCUITS 



363 



47k 



2.2k 



1.2 MSI 




COUNTER 
I NG CIRCUITS 



o-H> 



PREAMP FOR CMOS LOGIC— Combination of 
CA3130 and CD4010 ICs provides broad fre- 
quency response at very low power levels, as 
required for driving frequency counter. Diodes 
protect input from overvohtage. Amplifier offset 
control pot is used as trigger level control. Input 
sensitivity of amplifier/trigger combination is 50 
mV P-P from 1 Hz to 1 MHz.— R. Tenny. Counter 
Pre-Amp Matches CMOS Logic Capability, EDN 
Magazine, Sept. 20, 1976, p 114 and 116. 



3-35 pf 



0.001 MF 



100 MHz 

— 'Di — 



510 

f W\ OVee 



■7- 



1/4 
MC10102 



€> 



-O 100 MHz 



0.15 mH 



-,( 



MA 
MC10102 



O^ 



510 



100-MHz CRYSTAL OSCILLATOR— Developed 
for frequency counter that uses standard ECL 
components. Crystal can be changed to 10 MHz 
when measuring TTL performance. — W. R. 
Blood, Jr., "Measure Frequency and Propaga- 
tion Delay with High Speed MECL Circuits," 
Motorola, Phoenix, AZ, 1972, AN-586. p 3. 




300-MHz PRESCALER— Divides input frequency 

by 10 for extending range of digital frequency 

counter up to prescaler limit of 300 MHz. Read- also gives circuits of high-resolution counters fying the Digital Frequency Counter, Ham 

ing of counter must be multiplied by 10. Article using CMOS TTL devices.— H. E. Harris, Simpli- Radio, Feb. 1978, p 22-25. 



THREE TIME-BASE WINDOWS— Intersil 7207A 
crystal-controlled timer generates precision 
gate windows of 10 ms, 100 ms, and 1 s for use 
as time bases, calibration markers, or gate tim- 
ers for frequency counters such as 7208. — B. 
O'Neil, IC Timers— the "Old Reliable" 555 Has 
Company, EDN Magazine, Sept. 5, 1977, p 89- 
93. 



II 



+5V 

1 



7207A 

TIME 
BASE 



20 pF l20t>F 



SEGMENTS 
MUX LED DISPLAY 



o i~i o o i~i o oi 
u /_/ /_/ <_/ o i-i /_/ r 




FREQUENCY INPUT 



GATE WINDOW SELECT 



364 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




V oui 

TO CMOS 
"COUNTER 



1N914 



LOW-DRAIN 2-MHz FRONT END— Simple 
CMOS linear front end for 5-MHz battery-oper- 
ated counter reduces power drain and makes it 
proportional to input frequency. With no input, 
drain is only a few microamperes. Half of 
MC 14583 CMOS Schmitt trigger forms front 
end operating from single 6-V battery used in 
counter. Upper frequency limit is about 3 MHz, 
and input sensitivity is 400 mV. — D. Aldridge, 
CMOS Counter Circuitry Slashes Battery Power 
Requirements, EDN Magazine, Oct. 20, 1974, p 
65-71. 



CHAPTER 32 

Frequency Divider Circuits 



Provide division ratios in range from 2 to 29 for clock-signal generators, 
receivers, transmitters, and event counters. See also Clock Signal, Digital 
Clock, Frequency Multiplier, Frequency Synthesizer, and Logic chapters. 



V, 852 



DIVIDE BY 7 — Requires only two different types 
of chips. Input clock is alternately inverted and 
noninverted by gates operating in conjunction 
with 3 bits of storage using 852, to give square- 
wave output at one-seventh of clock fre- 
quency.— C. W. Hardy, Reader Responds to Odd 
Modulo Divider in July 1st EDN, EDN Magazine, 
Oct. 1,1972, p 50. 




'/. 846 



rJD—- 




S-REG 
A 



1/2N 



J L 



I 



DIVIDE BY 9 WITH SHIFT REGISTER— Uses 7496 
as 5-bit shift register, 7486 as EXCLUSIVE-OR 
gate, and 7404 as inverter to give division of 
square-wave input frequency by 9 while main- 
taining 50% duty cycle at output. Article covers 
connection changes needed for other division 
ratios. With 8-bit shift register, circuit will divide 
by as much as 15. Addition of 7486 EXCLUSIVE- 
OR gate across any outputs, as shown by 
dashed lines, makes effective output half that 
of basic TTL circuit. — J. N. Hobbs, Jr., Divide-by- 
N Uses Shift Register, EDN Magazine, Oct. 5, 
1976, p 108. 



365 



366 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 















A 
O 








B 
O 










■ +5V 
















preset 
J 

FF, 

K Q 
. clear 




preset 
J Q 

FF 2 

clock 

K 

clear 
























_ 


G 2 
































1 +5V 


s 3 




I+5V 




+ 5V 




Pb 










u 










input 




J— N 


' 










put 








+ 5V 


^4 



A 


B 


division 
ratio 


1 


1 


4 





1 


3 








2 



6,-64 each V* 74SOON 
FF, & FF a each 1 /2 74S112N 



DIVIDING 40-60 MHz BY 2, 3, OR 4— Division 
ratio is controlled externally by making control 
terminals A and B high (1) or low (0), as given 
in table. Developed for use in receiver requiring 
local oscillator covering 10 to 30 MHz. Counter 
simplifies tuner design. — C. Attenborough, Fast 
Modulo-3 Counter, Wireless World, Aug. 1976, 
p52. 



AF DIVISION BY 2 TO 1 1— Ratio of C2 to C1 de- 
termines division ratio, as given in table. When 
C2 charges to peak point firing voltage of 02, it 
fires and discharges C2, so CI charges to line 
voltage. 02 then turns off. Next cycle begins 
With another positive pulse on base of Q1, dis- 
charging CI. Division range can be changed by 
utilizing programmable aspect of PUT Q2 and 
changing ratio of resistances. — R. J. Haver and 
B. C. Shiner, "Theory, Characteristics and Ap- 
plications of the Programmable Unijunction 
Transistor," Motorola, Phoenix, AZ, 1974, AN- 
B27,p9. 



r^- 



R1 
3.9 k 
O WV- 



R2 
2.2 k " 



<: 



C1 

-\<r 



Q1 
MPS6512 



D1 
1N4001 



X" 



Q2 

MPU131 



Y 



• R4 

: 5.1 k 



_J_ 





<=1 


<=2 


Division 


0.01 (if 


0.01 (if 


2 


0.01 LiF 


0.02 /iF 


3 


0.01 flF 


0.03 /IF 


4 


0.01 /iF 


0.04 /iF 


5 


0.01 \lf 


0.05 [IF 


6 


0.01 pf 


0.06 /iF 


7 


0.01 /if 


0.07 /iF 


8 


0.01 /iF 


0.08 /<F 


9 


0.01 mf 


0.09 /iF 


10 


0.01 /iF 


0.1 /iF 


11 




-0 + 12V 



7~ 



OUTPUT 

r o 



X 



DIVIDER FOR 7 MHz— Used after 7-MHz VFO of 
40-meter transmitter, to provide 3.5 MHz as re- 
quired for operation in 80-meter band. Half of 
7474 TTL D flip-flop U1 is connected in divide- 
by-2 configuration. U2 provides required well- 
regulated 5-V source. Q1 clips negative-going 
portion of 7-MHz sine wave to prevent damage 
to 7474. Square-wave 3.5-MHz output from U1 
is applied to source-follower Q2 which drives 
class A amplifier output stage 03. RFC1 and 
RFC2 are 10 pH. C1 is 6.8-/1F 10-V tantalum. C2 
is 100-pF mica. L1 is 41 turns No. 26 enamel 
spaced to fill entire T-80-2 core, to give 10 /iH. — 
S. Creason, A VFO Frequency Divider, QST, 
Nov. 1976, p 23-24. 



FREQUENCY DIVIDER CIRCUITS 



367 



□ DUTY CYCLE 
CONTROL 

"" R, 




■WV— OV* 



"innnr 



_TLTU 



DIVIDER WITH PULSE SHAPER— Half of Exar 
XR-2556 dual timer divides input pulse fre- 
quency by 2 or 3, and other half shapes output 
pulse by controlling duty cycle over range that 
can be adjusted from 1 % to 99% with R 2 . Supply 
voltage can be 4.5-16 V.— "Timer Data Book," 
Exar Integrated Systems, Sunnyvale, CA, 1978, 
p 23-30. 



DUAL-TIMER TONE STEPPER— One section of 
RS556 dual timer is connected as free-running 
astable MVBR for supplying pulses to trigger 
input of other section connected as mono 
MVBR driving loudspeaker. When both MVBRs 
are adjusted so one trigger pulse initiates each 
timing period and no trigger pulses occur dur- 
ing timing periods, output tone has frequency 
of free-running MVBR. With two trigger pulses 
per timing cycle, every other trigger pulse is ig- 
nored and tone is at half frequency. With three 
trigger pulses per cycle, output is one-third of 
frequency. Can be used for classroom demon- 
stration of electronic music; settings of R1 and 
R3 can be adjusted to give tones resembling vi- 
olin, bagpipes, or almost any other instru- 
ment.— F. M. Mims, "Integrated Circuit Proj- 
ects, Vol. 6," Radio Shack, Fort Worth, TX, 1977, 
p 70-78. 



Rl 
500K 



rfri iui m riii noi rfi ri 



ICl 
RS556 
ITOPI 



U |2| (3j (_4j |5j |_6j |7| 



• IMF 



ad=. ±: « 



.01 uF 



T5 



100 K 



X 



R4 



V+ ( + 10Vto+15V) 



Output 
(1 kHz) 




PLL DIVIDER— Simple phase-locked loop is suit- 
able for generating integral submuftiples M of 
input frequency. Values shown give M of 2. 
Square-wave input reference is limited in am- 
plitude to supply voltage by first CMOS inverter 
A 3A . RC network R 9 -Cj integrates output to give 
2 V P-P triangle across C 2 for sampling by sam- 
ple-and-hold switch sections S, and S 2 of 4016 
CMOS analog switch. Sampled error voltage of 
loop, stored on C„2, is read out by FET amplifier 
A 2 . Amplified error voltage is applied to A, 
through R 5 to induce changes in center fre- 
quency of A, as required to maintain locked con- 
dition.— W. G. Jung, "IC Timer Cookbook," 
Howard W. Sams, Indianapolis, IN, 1977, p 220- 
224. 



368 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Hnput bias network 



UHF PRESCALER— Uses FairchHd 11C06 700- 
MHz D flip-flop as dhride-by-20 UHF prescaler 
with toggle rates in excess of 550 MHz from 
to 75°C. Amplifier may be used in place of input 
bias network shown. Developed for use with 
95H90 decade divider. Unused CP and D inputs 
are tied to ground. — D. Schmieskors, 1200-MHz 
Frequency Scalers, Ham Radio, Feb. 1975, p 38- 
40. 



¥• 



¥ 




■oi J 4) y 



O 




+5V 



+5V 



+5V 



+5V 




DIVIDE BY 15— Input clock is alternately in- 
verted and noninverted by gates operating in 
conjunction with 4 bits of storage using 852 JK 
flip-flops, to give square-wave output at 1/15 of 
clock frequency. — C. W. Hardy, Reader Re- 
sponds to Odd Modulo Divider in July 1st EDN, 
EDN Magazine, Oct. 1, 1972, p 50. 



CLK 



DIVIDER 


DATA 


RATIO 


INPUTS 


N 


D C B A 


3 


Q Q 


5 


1 Q 


7 


Q Q Q 


9 


1 Q 


11 


1 Q Q 


13 


1 1 Q 


15 


Q Q Q Q 


17 


1 Q 


19 


1 Q Q 


21 


1 1 Q 


23 


1 Q Q Q 


25 


1 1 Q 


27 


1 1 Q Q 


29 


1 1 1 Q 



•o 

BORROW (2) 




FF, -Q0 
FF,-Q f-\ 



3 TO 29 ODD-MODULO— Basic divider using 
74193 4-bit up/down counter and single 7474 
dual D flip-flop provides any odd number of di- 
vider ratios from 3 to 29 by changing feedback 



-3.5- 



connections as shown in table, all with sym- 
metrical output waveforms. Based on writing 
any odd number N as N = M + (M + 1), where 
M is integer. Circuit forces counter to divide al- 



-3.5- 



ternately by M and M + 1 . Connection shown is 
for divide-by-7. — V. R. Godbole, Simplify De- 
sign of Fixed Odd-Modulo Dividers, EDN Mag- 
azine, June 5, 1975, p 77-78. 



FREQUENCY DIVIDER CIRCUITS 



369 



slj 



'A 852 



d 



K Q 



IE 



[ A t | % 846 [ A 2 j 



CLK I / 



+5V % ? 52 CLK + 5 



% 846 



~\l i l- J U i 



SYMMETRICAL * 5 



DIVIDE BY 5 — Requires only two digital chip 
types. Input clock is alternately inverted and 
noninverted for clocking divide-by-3 counter, to 
give effect of dividing by Vk which toggles A 3 to 
give symmetrical divide-by-5 output with 50% 
duty cycle for pulses. Article gives timing dia- 
gram and traces operation of circuit. — C. W. 
Hardy, Reader Responds to Odd Modulo Divider 
in July 1st EDN, EON Magazine, Oct. 1, 1972, p 
50. 



SQUARE-WAVE DIVIDER— Divides input 
square wave by 1, 2, 5, or 10 depending on 
which switch is open. Signal at OUT-1 is in- 
verted with respect to input, and OUT-2 is non- 
inverted.— Circuits, 73 Magazine, June 1977, p 
49. 




^OUT-l 




d 



4x4 ARRAY 
OFSPST 

SWITCHES 



A 
KBM 


B 


C D 
MM74C922 


OSC 


Xj 


X 2 X, Y4 Y 3 Y 2 Y, 



PROGRAMMABLE COUNTER— Input frequency 
can be divided by any number between 1 and 
16 by pressing appropriate key on keyboard 
connected to National MM74C922 16-key en- 
coder. Output frequency is symmetrical for odd 
and even divisors. Can be used for simple fre- 
quency synthesis or as keyboard-controlled 
CRO trigger. Operates over standard CMOS 
supply range of 3-15 V. Typical upperf requency 
limit is 1 MHz with 10-V supply. Circuit uses two 
MM74C74 dual D flip-flops and MM74C86 EX- 
CLUSIVE-OR package.— "CMOS Databook," 
National Semiconductor, Santa Clara, CA, 1977, 
p 5-50-5-51. 



370 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




Q,-2N5716 
O.- 2N4403 
Q 3 - 2N4403 
Q 4 - MPS 918 
D,- 1N5236 



10-MHz FRONT END— Front-end design for bat- 
tery-operated 5-MHz counter consists of FET 
and bipolar buffer followed by Schmitt trigger 
made from MC75108 dual line receiver. Circuit 
operates linearly up to 10 MHz with 25-mV input 
signal. Requires swings from logic (0 V) to 



logic 1 (about 10 V), for which suitable counter 
circuit is given in article. Accepts any input 
waveform shape and level. — D. Aldridge, CMOS 
Counter Circuitry Slashes Battery Power Re- 
quirements, EDN Magazine, Oct. 20, 1974, p 65- 
71. 



5 MHz 

o 



74163 
CLK CLR 

2° 2' 2 2 2 3 



2 MHz 





o 




D Q 

FF z 
CK Q 








l© 



7474 


' 



1/6 7404 



1 MHz 
'® 0UT 



7420 






SYMMETRICAL DIVIDE-BY-5 CLOCK— Uses 
74163 counter to generate two phases of 1-MHz 
clock pulse with 50% duty cycle from 5-MHz 
system reference. One phase is decode of binary 
4 from counter, while other is decode of 1 



D Q 

FF ,_ 

CK Q 

— v~ 



r^- 



clocked at midbit time. Both phases are recom- 
bined in gate G, to give 2-MHz clock that toggles 
FF 2 to generate desired 1-MHz output. — L. A. 
Mann, Divider Circuit Maintains Pulse Symme- 
try, EDN Magazine, July 1, 1972, p 54-55. 



SN7474 



C d D C S d Q Q 

n 



1N4154 



l_y out 



J CLOCK K 
A 



J CLOCK K 
B 



J CLOCK K 

CLEAR 
Q C Q 



CLK/51 

clk jiJVTj~uTJXJT_artJLr 




CLK/5— I 

(50% DUTY CYCLE) 



DIVIDE BY 5 WITH TWO GATES AND 3 BITS— 
Arrangement shown for dividing clock input 
frequency by 5 requires only two gates from 846 
IC and 3 bits of 852 JK flip-flop storage to give 



square-wave output pulses having 50% duty 
cycle. — C. L. Maginniss, Another Reader Re- 
sponds to Odd Modulo Divider, EDN Magazine, 
Oct. 15, 1972, p 57. 



-rLrLTLTLT 



output 

SWITCHED DIVIDER FOR BINARY COUNTER— 
Simple circuit provides method of switching 
division by two into or out of stream of clock 
pulses. Output is in phase with input and free 
of spikes. Switching requires only one D-type 
flip-flop and one inverter. When control is high, 
logic action gives normal connection for divi- 
sion by two, using D-type flip-flop; inverter then 
restores phase. — J. M. Firth, Control of a Binary 
Counter for Division by One or Two, Wireless 
World, Jan. 1975, p 12. 



CHAPTER 33 

Frequency Measuring Circuits 



Includes direct-reading heterodyne frequency meters, synchroscopes, dip 
meters, tuning indicators, frequency-to-voltage converters, tachometers, and 
monitors showing when input frequency or pulse rate is above or below 
reference, for variety of frequencies in range from 1 Hz through power-line 
and audio values to 150 MHz. See also Frequency Counter and Frequency 
Multiplier chapters. 



JUL 




PRF MONITOR— Upper channel latches when 
pulse repetition frequency of train of pulses is 
higher than specified limits, turning on above- 
limit LED driven by JK flip-flop FF,. Lower chan- 
nel latches and turns on its LED when PRF is 
below second specified limit. Upper channel 
also detects single noise pulse, while lower 
channel detects single missing pulse. After off- 
limit indication, circuit must be reset. — L. Birk- 
wood and D. Porat, PRF Monitor with Adjusta- 
ble End Limits, EDNBEE Magazine, Feb. 1, 1972, 
p 57-58. 



INPUT 
FREQUENCIES 



EXCLUSIVE -OB 
GATES: 7486 




fat pbpoi icwrv mci i av a » ,. ... wise. When F1 is less than F2, dot rotates coun- 

ts^ ^Tt,, =n ^y- Appar , en * rota - rfbeatfrequency between two tone oscillators, terclockwise. When F1 equals F2. dot does not 
fton of dot on four-LED d.splay g.ves indication When F1 is greater than F2, dot rotates clock- move.-Circults, 73 Magazine, July 1977 pK 



371 



372 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




i hvw • — w* — e- 



ICXVF- 
6V 



L^ik— I 



GRID-DIP METER— Uses ordinary No. 48 or 49 
L AMP pilot lamp as resonance indicator. Will oscillate 
-f? ) at frequencies up to 12 MHz. Wind LI to cover 
r^-^ desired frequency ranges. — Circuits, 73 Maga- 
zine, April 1973, p 133. 



LED SYNCHROSCOPE— Circuit uses four LEDs 
to indicate direction of phase error as correct 
setting is approached when tuning oscillator to 
standard frequency. Lamps form display that 
rotates once per cycle at reference frequency, 
with brightness of each lamp being modulated 
at frequency of oscillator being adjusted. Dis- 
play thus appears to have frequency equal to 
difference between two signal frequencies, ro- 
tating in direction indicative of sense of fre- 
quency difference. Mount lamps on smallest 
possible circle. Diode and LED types are not crit- 
ical. — R. H. Pearson, An L.E.D. Synchroscope, 
Wireless World, Sept. 1974, p 321. 



10k 




"*C 



BC109 

r® 

-M— 



-270° 



outputs from 5V reference oscillator 




150 12N3702 




O+SV 



€)@ 




* SHELL OF J2 
INSULATED 
EXCEPT AS INDICATED, DECIMAL FROM CASE. 

VALUES OF CAPACITANCE ARE 
IN MICROFARADS (jiF); OTHERS 
ARE IN PICOFARADS I pF OR jijiF); 
RESISTANCES ARE IN OHMS; 
» 1000. M. 1000 000 



AUDIBLE DIPPER— Designed for use by blind 
radio amateurs, but tone indication has advan- 
tage of permitting anyone to concentrate on 
equipment while checking antenna, tracking 
parasitics, or neutralizing amplifier with dip 
meter. Plug-in coils L1-L6 am Heathkit parts 40- 
1689 through 40-1695. Q1, Q2, and Q4 are Radio 
Shack RS-201 1 or equivalent:, and Q3 is RS-2021 
or equivalent. Pitch of tono heard from loud- 
speaker drops sharply when tuned circuit of dip- 
per becomes loaded by external source. — W. E. 
Quay, An Auditory Dip Oscillator, QS7", Sept. 
1978, p 25-27. 



FREQUENCY MEASURING CIRCUITS 



373 



TRIGGER 
IWUT " 



JT l 



<►— • 



10k 



C, . 
0033i/F ' 



TRIGGER BOOST 
OGIC V* 



V REf COLLECTOR 



, Rt 
• 2.7k 



R2 

1.0k TRIM 

;r3 

. «.7k 



CI 
'lOV 



FREQUENCY-TO-VOLTAGE CONVERTER— Na- 
tional LM122 timer is used as tachometer by 
averaging output pulses with simple filter. 
Pulse width is adjusted with R2 to provide initial 
calibration at 10 kHz. Linearity is about 0.2% for 
output range of 0-1 V. Analog meter can be dri- 
ven directly by connecting it in series with R5. 
Supply can range from 4.5 to 40 V. — C. Nelson, 
"Versatile Timer Operates from Microseconds 
to Hours," National Semiconductor, Santa 
Clara, CA, 1973, AN-97, p 10. 



RATE DETECTOR— Only three ICs are used to 
sense pulse rate of input signal with high ac- 
curacy. For monitoring frequency, two such cir- 
cuits can be used, with one set to upper fre- 
quency limit and other to lower limit. Output is 
high when input pulse rate is above set point 
and low for frequencies below set point. Fre- 
quency of set point is reciprocal of monostable 
delay time (f = 1/0.32R 2 C 2 ).— J. W. Poore, Three 
ICs Accurately Sense Pulse Rate, BDN Maga- 
zine, Aug. 15. 1972, p 53. 



INPUT 

o— 



R, 



' Ik -r* 

(—vVA-»PULLUP ~ 

+5Vq I. •_ 

5fco.O' '' 5 

3NDO e-. 



(B) 



101(C) 



470pF 




OUTPUT 
(ABOVE) 



REF TYPE +5V PULL-UP GND 

G, SN7400N 14 7 

FF 2 SN54121N 14 5 7 

FF 3 SN7474N 14 2,4, 10, 13 7 



Ri: 

5k6 



D,' 
OA202 



BO- 



D 2 I 



AO- 



10k 

-WV- 



R3' 
10k' 



MPSA60' 



D 3 I 
3V9' 



^ 



C1 
22n 

-II- 



D 4 ' 
OA202' 




_ C 2 
T" 47 H- 
16V 



STANDBY-GENERATOR FREQUENCY ME- 
TER— Developed for use with 10-60 VAC gen- 
erator driven by lawn mower engine, as guide 
for adjusting speed manually to give correct 
power-line frequency. Output of alternator, 
connected to A and B, is converted to regulated 
10 VDC by R„ D„ D 2 , and C 2 . Same input voltage 
is squared by Tr, and fed to Tr 2 through differ- 
entiating circuit. Current pulses developed in 
collector circuit of Tr 2 have constant width and 
varying repetition rate depending on input fre- 
quency. Inertia of meter movement provides in- 
tegration required to give steady reading that 
changes only with input frequency. Meter scale 
is calibrated from to 100 Hz, with R, adjusted 
to give correct reading when 10-60 VAC line 
voltage is applied to input. Power transformer 
must be used to boost output of alternator to 
correct AC line voltage. — J. M. Caunter, Low- 
Cost Emergency Power Generator, Wireless 
World. Feb. 1975, p 75-77. 



374 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



TRANSISTORS FOR BC-221— Old BC-221 fre- 
quency meter can be modernized by replacing 
its three now-scarce tubes with four 2N3819 N- 
channel JFETs and changing supply to single 9- 
V battery. VT167 (6K8) mixer-oscillator is re- 
placed by two JFETs with R2, R3, and C1 
mounted inside octal plug. Resistance values 
may need some adjustment. Cut and insulate 
original leads to pins 2, 4, and 7, and connect 
top-cap clip of mixer tube to pin 4. VT116-B 
(6SJ7-Y) tube used for VFO is replaced by single 
2N3819 connected as for Q1. Add R1 in parallel 
with plate load resistor; value depends on par- 
ticular FET used, and can range from 1 to 6800 
ohms (1500 is typical). VT116 (6SJ7) beat-fre- 
quency amplifier is replaced by 2N3819 
mounted same as for 0.1. Place 4K across 15K 
load resistor of VT116-B and replace 300-ohm 
cathode resistor with one giving 1-mA source 
current (typically 1K to 3.3K). Total current drain 
is about 3 mA. Try 3-10 pF capacitor between 
gate and drain of Q3 if circuit does not oscil- 
late.— R. S. N. Rau, Solid-State BC-221 Fre- 
quency Meter, QS7, Feb. 1977, p 35-36. 



CRYSTAL 

OSCILLATOR 

03 


r\ GRID CAP 

OCTAL 1 MIXER 
PLUG 02 


/-" 


~N° 




' \ D^"" 


~\ 


G l» 


s 


TO:!) .( 


4 « 


\* 


' 


V. 


y 


/H 




_> 



750p 
CONNECTIONS VIEWED FROM INSIDE OF OCTAL PLUG 



FORMERLY +135 V 



BT1 -=. 

9V -=r 

BATTERY ~~ 



^ 29B 

-cr o 



POWER SWITCH 



7£T 



^r 



29A 



CUT 
— X — 




CONNECTIONS TO 
ra 5<t ra \ FET VIEWED 
^r^y") FROM INSIDE OF 
07\/ 20J ° CTW - PLUS 




METHOD OF MOUNTING THE FET, 01 AND 02 
(B) 



8T 



>I9 
, 56 k 



'1500 



FORMERLY +6V 



VTH6B I J 

6SJ7-Y \l 1/ 

OSCILLATOR \ 

VALVE 



PARALLELING THE ANODE LOAD RESISTOR U9) BY R1 
(C) 



Frequency range 
(MHz) 


1-1/2 


Coil diameter and turns 
1-3/8 1-1/4 1 (inches) 


Wire size and 
coil const. 




38 


35 


32 


25 (mm) 




.08 - 0.2 
0.205 - 0.6 
0.5- 1.4 
0.95 - 3 
2.6-6 


700 

220 

90 

40 

18 


750 

240 

100 

45 

20 


800 

256 

110 

49 

22 


1000 

310 

140 

64 

29 


No. 30 enam., 5 pies. 
No. 30 enafn., 5 pies. 
No. 30 enam., close wound 
No. 22 enam., close wound 
No. 22 S. C. enam., 1-3/4" 
long (44 mm) 


5.5- 15 


7 


8 


9 


12 


No. 22 S. C. enam., 1-1/2" 
long (38 mm) 


14-35 


2 

(11/16" 


2 

(3/4" 


2 

(1") 


2-1/2 
11") 


No. 22 S. C. enam., length 
indicated at bottom of 




(17mm) 


(19 mm) (25 mm) 


(25 mm) 


column. 



J? 






1 

2 




1 




2 






GATE DIPPER — Used to determine resonant 
frequency of tuned circuit, provide signal for re- 
ceiver alignment, and make antenna measure- 
ments. Table gives winding data for plug-in 
coils LI. Parts values are not critical. T2 is tran- 
sistor interstage audio transformer with 10,000- 
ohm primary and 2,000-ohm secondary in meter 
circuit. JFET Q1 is used in common-drain circuit 
followed by PNP bipolar transistor, with gate 
junction of JFET acting as reictifier. Dip meter 
M1 measures gate current. V/hen tuned circuit* 
of dipper is loaded by coupling it to external cir- 
cuit, power is absorbed and meter reads dip oc- 
curring when L1-C1 is tuned 1:o resonance with 
external circuit. R1 is regeneration control. 
Audio amplifer Q3-Q4 using 2N4125 or HEP52, 
optional, helps in listening to signals picked up 
by tuned circuit or enhances display on CRO. 
Can be used as field-strength meter if antenna 
is plugged into J1 . — B. Clark, A Hybrid Gate-Dip 
Oscillator, QST, June 1974, p 33-37. 



^\ t -^> 



FREQUENCY MEASURING CIRCUITS 



375 



SIGNAL INO 




REO RED 



FREQUENCY INDICATOR— Circuit furnishes 
green indication at resonance and red for either 
side of resonance. Uses Monsanto MV5491 dual 
red/green LED, with 220 ohms in upper lead to 
+5 V supply and 100 ohms in lower +5 V lead 
because red and green LEDs in parallel back-to- 
back have different voltage requirements. Use- 
ful for SSTV, RTTY, or subaudio-tone indication 
for control purposes on FM. Circuit requires two 
driver ICs and one section of hex inverter IC, 
with any suitable active filter used to form level 
detector for signals at desired frequency. — K. 
Powell, Novel Indicator Circuit, Ham Radio, 
April 1977, p 60-63. 




1 "zzzl xt tr l <10» 

JT CAN BE _l_ _L _L 



-►v 0UT 



INPUT t 
20 mV TO *28V ~ ~ - 

FREQUENCY-DOUBLING TACHOMETER— Con- 
nection shown for National LM2907 IC provides 
output pulse each time sine-wave input from 
magnetic pickup crosses zero, for use in digital 
control system. Width of each pulse is deter- 
mined by size of CI and supply voltage used. 
Circuit serves for doubling frequency presented 
to microprocessor control system. — "Linear 
Applications, Vol. 2," National Semiconductor, 
Santa Clara, CA, 1976, AN-162, p 12-13. 




DIPPER— Circuit of Heath HD-1250 solid-state 
dip meter covers 1.6-250 MHz range with six 
plug-in coils. — The Heath HD-1250 Dip Meter, 
QST, Jan. 1976, p 38-39. 






BICYCLE SPEED ALARM— Useful for long-dis- 
tance bicycling, to indicate when rider drops 
below predetermined minimum speed. Speed 
sensor is reed switch attached to frame and 
tripped once per revolution by permanent mag- 
net mounted on wheel. Rate at which switch 
closes determines level of DC voltage produced 
by circuit. When voltage drops below preset 
level determined by 100Kpot, output transistor 
comes on and energizes relay controlling bicy- 
cle horn or other signaling device. Supply can 
by 9-V transistor battery. Transistor reading 
should be high enough to handle relay used. — 
J. Sandler, 9 Projects under $9, Modern Elec- 
tronics, Sept. 1978, p 35-39. 



of bicycle 

Magnet 
on wheel 



.OVf =1= 



3.3KH 
i— WV 




+ V to pin 14, return to pin 7 ft7 



376 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




10K 

r-VW 



GATE DIPPER— Solid-state version of vacuum- 
tube grid-dip meter gives dip from 50 to about 
20 im.A on most bands in range of 1 .8 to 150 MHz 
when dipper is held 1 inch away from resonant 
circuit under test. Uses Siliconix 2N5398 UHF 
JFET, but MPF107 (2N5486) can also be used. 
Coil tap position is more critical at higher fre- 
quencies; adjust tap for most pronounced dip. 
Article gives coil data for five frequency 
ranges.— C. G. Miller, Gate-Dip Meter, Ham 
Radio, June 1977, p 42-43. 



10K 
j-A/W- 



5v. peak square .022 
wave input ) — ~jf 
0-10KH2 



6.8K 
+ 15v.< WV 



10 mA 
METER 
FSD ' 6000 RPM 




STARK COIL 
0IST. TERMINAL 




0-10 kHz TO 0-10 VDC— Raytheon 4151VFC 
voltage-to-frequency converter is used in re- 
verse as linear frequency-to-voltage converter. 
Applications include use in pairs as complete 
data transmission system, for remote monitor- 
ing of DC voltage such as output of SWR bridge 
located at junction of antenna with transmis- 
sion line. DC voltage is changed into audio volt- 
age at remote location, sent over lines, then 
changed back to DC at readout location. Line 
characteristics do not affect frequency of audio 
signal. — J. J. Schultz, A VoJtage-to-Frequency 
Converter IC with Amateur Applications, CO. 
Jan. 1977, p 39-41 and 75. 



SPARK-COIL TACHOMETER— Input to National 
LM2917 tachometer IC is taken from spark-coil 
distributor terminal of gasoline engine. Fre- 
quency of input signal is converted to voltage 
for driving meter. Circuit is set up for number of 
cylinders on engine by adding link for appropri- 
ate timing resistor. Zener protects IC from tran- 
sients found in auto battery circuit. — "Linear 
Applications, Vol. 2," National Semiconductor, 
Santa Clara, CA, 1976, AN-162, p 9-10. 



RF SIGNAL INPUT 



HETERODYNE FREQUENCY METER— Circuit 
consists of 1-2 MHz oscillator Q1, untuned 
mixer X1, and AF beat-note amplifier 02. C4 is 
calibrated to read directly in frequency from 1 
to 2 MHz, using accurate unmodulated RF signal 
generator. After calibration, unknown RF signal 
input frequency is fed into meter for zero-beat- 
ing with harmonics of calibrated oscillator. 
Magnetic headphones plugged into J1 make 
beat note audible. On second harmonic, dial of 
C4 covers 2-4 MHz; on twentieth harmonic, 
coverage is 20-40 MHz. L1 is 65 turns No. 28 
enamel on 1-inch form, tapped 20 turns from 
ground. L2 is 10 turns No. 28 enamel close- 
wound around center of LI . — R. P. Turner, "FET 
Circuits," Howard W. Sams, Indianapolis, IN, 
1977, 2nd Ed., p 144-146. 




FREQUENCY MEASURING CIRCUITS 



377 



to+15V 



R 6.8k<; 



HIGH-PRECISION F/V— Use of integrator 
opamp with frequency-to-voltage connection 
of RM4151 converter gives increased accuracy 
and linearity for converting square-wave inputs 
of 0-10 kHz to proportional output voltage in 
range of -10 V to V. — "Linear Integrated Cir- 
cuit Data Book," Raytheon Semiconductor Di- 
vision, Mountain View, CA, 1978, p 7-39. 




FREQUENCY 
INPUT 



5Vp-p 

SQUARE 

WAVE 



O 

VOLTAGE 

OUTPUT 

10V V n 



'in 0.022 



Yin 

SQUARE-WAVE 
INPUT 



(at 







S/vV- 



tr 100 



100k RC4131 



CALIBRATION: 

1. SET f |N TO 10 Hz. ADJUST OFFSET FOR -10 mV OUTPUT. 

2. SET f.„ TO 10 kHz. ADJUST OFFSET FOR -10V OUTPUT. 




*m. ' A 4558 
^SECOND-ORDER. 



~ LOWPASS 
FILTER 



F/V WITH 4151— Uses Raytheon 4151 as fre- 
quency-to-voltage converter for generating cur- 
rent pulses having precise amplitude and width . 
Average value of output pulse train is directly 
proportional to input frequency. Article gives 
design equations. Response time can be im- 
proved and ripple reduced by using second- 
order (double-pole) low-pass filter as shown in 
diagram (b). Ripple is less than 0.1 V P-P over 
range of lOto 10,000 Hz when R, and R 2 are 100K 
and C, and C 2 are 0.1 fiF.— T. Cate, IC V/F Con- 
verters Readily Handle Other Functions Such as 
F/V, A/D, EDN Magazine, Jan. 5, 1977, p 82-86. 



378 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 








< 


c 
p 




_r~ 


a 


7 


6 5 






% v 






>— c 




VARIABLE 
ELUCTANCE 

MAGNETIC 


^rl 


y 




PICK UP 


J- CI — 

="0.01 U F^ 


2 


3 4 

il 1 

R1< — 1 — C2 <F 

00k S ^TM.o u f Si 



TACHOMETER USING MAGNETIC PICKUP— 
Signal frequency proportional to shaft speed 
being measured is fed into National LM2907 IC 
for conversion to output voltage that is propor- 
tional to input frequency. Output is zero at zero 
frequency. Quality of timing capacitor CI deter- 



mines accuracy of unit over temperature range. 
Use equivalent zener-regulated LM2917 IC if 
output voltage must be independent of varia- 
tions in supply voltage.— "Linear Applications, 
Vol. 2," National Semiconductor, Santa Clara, 
CA, 1976, AN-162, p 3-4. 



X" 



R2 R1 

10k 10k 

#-VV\-t-^VVv-t> 



GND 
8 



R3 
500k 

7 



-0"b 



"cc 




©c 



PLUG-IN COIL 
(SEE TABLE 7- 



© A il0OpF 
TUNING J- 



i ^-?^ ^ jc ©i 

200pf ^ \j71 s i 



© 



QW~ 



®. 



0-50 DC 
y MICRO-AMMETER 



FET DIP OSCILLATOR— High input impedance 
of FET makes performance comparable to that 
of tube-type grid-dip oscillator. Six plug-in coils 
are wound on Millen 45004 1-inch 4-pin forms 
or equivalent. Use 150 turns No. 32 enamel for 
1.1-2.5 MHz, 77 turns No. 28 for 2.5-5 MHz, 35 
turns No. 22 for 5-11 MHz, 17 turns No. 22 
spaced to 1 inch for 10-25 MHz, 8.5 turns No. 22 



-^A/V 1 

IK 



ON-OFF 



,1 



6V 
5 mA 



spaced to 1 inch for 20-45 MHz, and 4.5 turns 
No. 22 spaced to 1 inch for 40-95 MHz. Adjust 
R1 to set meter pointer to desired portion of 
scale before tuning for dip. R1 provides some 
control of volume when using headphones. — R. 
P. Turner, 'TET Circuits," Howard W. Sams, In- 
dianapolis, IN, 1977, 2nd Ed., p 134-136. 



SPEED SWITCH— National LM2907 tachometer 
IC is used as switch to energize load when input 
frequency exceeds value corresponding to pre- 
determined speed limit. Automotive applica- 
tions include use as overspeed warning that ac- 
tivates audible and/or visual indicator when 
auto speed exceeds legal limit or other desired 
value. Another application is increasing inten- 
sity of auto or taxi horn above predetermined 
speed such as 45 mph. Input is variable-reluc- 
tance magnetic pickup positioned against teeth 
of gear wheel; in typical setup, pickup output is 
16.6 Hz at 60 mph. Values shown for compara- 
tor-controlling components R1 and C1 (below 
IC) give switching operation at about 16.6 Hz at 
input. Report gives design procedure for other 
frequencies. — "Linear Applications, Vol. 2," Na- 
tional Semiconductor, Santa Clara, CA, 1976, 
AN-162, p 8. 




LINEAR 
SPECTRUM 
SIGNAL +5V 



ALARM FOR SPECTRUM ANALYZER— Circuit 
drives audible alarm when frequency of interest 
appears in spectrum range. Display cursor can 
be preset to initiate narrow search band in 
which f x is expected to appear. 100-//S pulse rep- 
resenting cursor position in display sweep trig- 
gers mono IC, so its output becomes window 
whose time-out is equivalent to band in which 
f x is center. Comparator A, supplies high output 
when f x appears. Simultaneous arrival of this 
signal and timer window at gate A sets output 
of left flip-flop high. At end of window period, 
right flip-flop also goes high and initiates alarm 
via Q,. Loss of f x stops alarm. — R. L. Messick, 
Alarm Simplifies Spectrum Analyzer Measure- 
ments, EON Magazine, Juno 5, 1978, p 152. 



FREQUENCY MEASURING CIRCUITS 



379 



v+ 



Input Pulse 
Train 

A 



68 kn 



0.01 m f" 



v+ 



A, 
322 



R/C 
V 



E 
GND 



R, 

loo kn 



T j-pvv 



R, 

10 Mn 



322 



•0.1, 



E 
GND 



R 4 
£10kn 
■X—o Alarm 
Output 
High = f > I 



SPEED ALARM — Frequency detector using two 
IC timers provides alarm output when input fre- 
quency is greater than reference frequency, cor- 
responding to overspeed. Calibrated mono 
MVBR A, produces fixed-width positive pulse 
across R 2 , with average voltage of pulse varying 
linearly with input pulse train frequency. Com- 
parator A 2 changes states when integrated out- 
put of R 3 -C 1 on pin 5 goes above or below 2-V 
voltage threshold of A 2 . With values shown, de- 
sired frequency is 1 kHz and circuit detects fre- 
quency variation of less than 1%. If low-fre- 
quency alarm is desired, connect logic input pin 
2 of A 2 to reference voltage (pin 4) instead of to 
ground.— W. G. Jung, "IC Timer Cookbook," 
Howard W. Sams, Indianapolis, IN, 1977, p 228- 
230. 




GRID-DIP OSCILLATOR— Millen 90652 solid- 
state grid-dip oscillator uses MOSFET operating 
in split-Colpitts circuit with resonating tank 
connected between drain and gate. Circuit is 
tuned by split-stator variable capacitor with 
rotorgrounded, chosen to cover 1.7 to 300 MHz 



with seven plug-in coils. Oscillator also func- 
tions as Q multiplier that increases sensitivity. 
RF voltage across tuned circuit is indicated by 
meter whose reading dips for resonance with 
coupled test circuit. Full-wave rectifier CR,-CR 2 
provides DC voltage for meter and some over- 



load protection for MOSFET. Meter is sup- 
pressed-zero type, with readings only for upper 
portion of current range. J 3 is provided for use 
with low-frequency coils.— W. M. Scherer, CQ 
Reviews: The Millen Model 90652 Solid-State 
Dipper. CQ, Sept. 1971, p 63-64, 66, and 96. 



+ 5V 



10 F+ 

O— 1| — >w\, •■ 

100k 



frequency 




TIL 209 etc 



HI-LO LED FREQUENCY DISPLAY— Apparent 
rotation of flashing LEDs around square indi- 
cates whether input frequency is above or 
below reference frequency. Input and reference 
waveforms may have any shape, because 
Schmitt triggers reshape both to give rectan- 
gular pulses which flip-flops divide by two so 



outputs are square waves with mark-space ra- 
tios at half original frequency. Square waves are 
gated together to produce rectangular pulse 
train having mark-space ratio that depends on 
phase difference between the two square 
waves. Logic is arranged to drive LEDs at rota- 
tion rate of half the difference between input 



and reference frequencies. Correct positioning 
of LEDs in square is shown on small diagram. 
Reference frequency input should be via 
BC108B (not shown), same as for input fre- 
quency.— C. Clapp, Beat-Frequency Indicator, 
Wireless World, Nov. 1976, p 63. 



380 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



r 



O 




3^ 



<TN ,0I< S 



■*v 0UT 



TACHOMETER WITH SQUARE-WAVE OUT- 
PUT— National LM2907 tachometer IC provides 
square-wave output at same frequency as sine 
wave generated by magnetic pickup, for use as 
line driver in automatic control system. — "Lin- 
ear Applications, Vol. 2," National Semiconduc- 
tor, Santa Clara, CA. 1976, AN-162, p 12-13. 



A o- 

Trigger 



R, 
560 kn 



'J 



C,*_|_ 
1500 pF*~ 



v+ 

9 (+9V to +15V) 



J0.1 M F 



TR 

L 

V, 

R/C 



B 

V+ 
A, 

322 c 

E 
GND 



■ \W- 



10 Mil 



3 
1500pF T 1500pF T 




3.9 kn 



loo kn 



DC Output 

Full Scale = 5 V 



"Let T = R, C, ; 



0.95 



FREQUENCY METER— High-precision f re- full-scale voltage value of +5 V. Two-pole filter 

quency-to-voftage converter can be used as fre- removes ripple from positive output pulses 

quency meter In laboratory. Input frequency acrossR,beforesignalisfedto3130opampthat Jung, "IC Timer Cookbook," Howard W. Sams, 

range up to 1kHz is converted to corresponding provides gain and zero adjustments. — W. G. Indianapolis, IN, 1977, p 192-196. 



FREQUENCY RANGE (Hz) 
50 500 5000 



9V0LT-=. 



INPUT 
I VRMS 




Ql 
2N2222 , 

UNKNOWN '°'* F i 0K /<P\ 

FREQUENCY ^(-JS^^T) 



PULSE SHAPING 
NETWORK 



DIFFERENTIATOR 



MONO PERIOD T- I.I R3C3 
MONOSTABLE 



AVERAGER 



50^A 
PANEL 
METER 



VOLTMETER 



AF METER — Timer IC1 forms basis for linear fre- gered by unknown input frequency. Article cov- pin 2. — G. Hinkle, IC Audio Frequency Meter, 73 
quency meter covering audio spectrum. Mono ers operation and calibration. Errata: pin 4 of Magazine, Holiday issue 1976, p 61. 
MVBR puts out fixed-width pulse when trig- 555 should be connected to pin 8 instead of to 



FREQUENCY MEASURING CIRCUITS 



381 



INPUT 



'MMCHOID 




ONESHOT 
i4(MC14528) T _ 



Q T ' 



RATE LOW OUTPUT 



0- 



RATE HIGH OUTPUT 
@ 



+ 15VO 



4 



-0+15V 



1N914 
-•— Wv^-«~ 



T.5M _L 



J4IMC14011) I G, 



'/i(MC14013) 
D FLIP FLOP 



S 



PULSE-RATE DETECTOR— Operates from 1 Hz 
to 2 MHz, providing one logic level when input 
rate crosses set point and opposite logic level 
when input rate falls below set point. Set-point 
rate is reciprocal of MVBR time, or 1/R,d. Two 
periods of input signal an sufficient for re- 
sponse to rate change. Value of d is R,C,/1.5 
x 10 6 .— -J. M. Toth, Versatile Circuit Forms Aer 
curate Pulse-Rate Detector, EDN Magazine, 
Aug. 20, 1977, p 142-143. 



F/V WITH OUTPUT FILTER— Two-pole low-pass 
active filter improves dynamic range and re- 
sponse time of Raytheon 4152 frequency-to- 
voltage converter. Ripple in output is less than 
0.02 V P-P above 100 Hz. Requires ± 15 V supply. 
Maximum input frequency is 10 kHz when C m is 
0.002 pF, R is 6.8K, and Co is 0.01 pF— "Linear 
Integrated Circuit Data Book," Raytheon Semi- 
conductor Division, Mountain View, CA, 1978, 
p7-48. 




LOW PASS FILTER 




~± 



-vw 



100 K 



— wv 

100 K! 





n«DC VOLTAGE WITH 
BOTH POTENTIOMETERS 
SET AT MID ROTATION 



MOSFET DB» METER— Output of grounded- 
drain Colpitis oscillator using RCA N-channet 
dual-gate MOSFET Q1 is detected by CR1 and 
amplified by 02 for driving meter. Frequency of 
oscillation depends on C1, C2, C3, and LI, and 



reaches 250 MHz when LI is reduced to hairpin. 
Table gives values of plug-in assembly L1-C1-C2 
for nine frequency ranges. Circuit was designed 
for 12- V supply but works well with 9-V battery 



FREQ. RANGE 


C1 


C2 


L1 


MHz 


pF 


PF 


TURNS 


2.3-4 


15 


15 


71-1/2 


3.4-5.1 


33 


10 


39-1/2 


4.8-8 


10 


33 


25-1/2 


7.9-13 


10 


33 


14-1/2 


12.8-21.2 


10 


33 


6-1/2 


21-34 


10 


33 


4-1/2 


34-60 


10 


33 


2-1/2 


60-110 


10 


33 


# 


90-200 


Not 


Not 


#* 




used 


used 





•denotes a 1-1/2 -turn coil of No. 18 enam. 
wire wound on a 1/2-inch form spaced 1/8 
inch between turns. It should be placed so 
that the coil is near the top of the coil form, 
•"denotes a hairpin loop made from flashing 
copper, 3/8-inch wide X 1-7/8-inch total 
length. 

All other coils are wound with No. 24 
enam. wire. 



shown if drain resistor R D is shorted. Battery 
drain is about 20 mA. AR coils are wound on 
Millen 45004 forms. — F. Bruin, A Dual-Gate 
MOSFET Dip Meter, OST, Jan. 1977, p 16-17. 



382 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



VOLTAGE 
OUTPUT 
to + 10V 
V r 



HVW 



f, 

FREQUENCY 022 (J ( 
INPUT O — If" 

"LTLT 

5Vp-p 

SQUARE 

WAVE 




2N4416 



•15V 



DESIGN EQUATIONS: 



-1 



Where K - 486 



Mi 



R B R C V 



11 RnC, 



0^-0 




F/V CONVERTER— Single-supply circuit uses 
frequency-to-voltage connection of RM4151 
converter to make output voltage vary between 
and +10 V as frequency of 5 V P-P square- 



wave input varies between and 10 kHz. — "Lin- 
ear Integrated Circuit Data Book," Raytheon 
Semiconductor Division, Mountain View, CA, 
1978, p 7-39. 



GATE-DIP FET OSCILLATOR— Meter indicates 
gate current, which drops whenever resonant 
load is placed on tank circuit of oscillator by 
bringing plug-in input coil near frequency 
source being checked. Uy opening switch to 
power supply, circuit can be used as absorption 
wavemeter; when signal at resonant frequency 
of dip-meter tank circuit is picked up, gate- 
source circuit of FET operates as diode detector 
for producing increase in meter reading. Values 
of plug-in coil and tuning capacitor depend on 
frequency range of interest. — E. M. Noll, "FET 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 2nd Ed., 1975, p 213- 
214. 



nput Signal 

Conditioning 

(See Text ) 



R 5 

25 kn 



Input 



2N2219 



Full-Scale 
Calibrate 5 

: R 6 

95.3 kil 




+ 15V 

o 



10 kn 



L 

V, 

R/C 



V + 



A 2 
322 



E 
GNO 



10 



12 



_ f 

— Tooo 

where, 

R a = 20 kn, t, " R, C, = 50 ,us, 

l 2 = 1 mA. 

+ R,, C,, R„, and F! b are stable, 
low-TC components. 



-O DC Output* 



Frequency 

used for input conditioning. A, is connected as 
HIGH-PRECISION F/V— Components of V/F con- MVBR A 2 either directly if pulsed or indirectly scaling amplifier and filter.— W. G. Jung, "IC 
verter are reconnected to provide F/V function, after conditioning. For low-frequency or slowly Timer Cookbook," Howard W. Sams, Indianap- 
Input frequency up to 10 kHz is fed to 322 mono changing waveforms, zero-crossing detector is olis, IN, 1977, p 192-196. 



CHAPTER 34 

Frequency Modulation Circuits 



Covers FM circuits used in broadcast receivers and transmitters for 
monophonic or stereo transmissions, along with FM radio communication 
circuits and power-line FM carrier systems. Includes tuning indicators, stereo 
decoders, SCA demodulator, and FM deviation meter. 



20-dB GAIN FOR 2 m— Input of 200 mW is am- 
plified to 20 W. Positive 20-V sources are sepa- 
rated so final stage can be amplitude-modu- 
lated; for FM, connect to single supply. 
Transistors require heatsinks. — Circuits, 73 
Magazine, May 1973, p 106. 



(to tig. 2) +12V 









tin 

- -V A- + 




REC65 1261-508) 


input 


output\p cioV 


TBA625B 



TUNER USES IC— Availability of Signetics 
NE563 IC having about 180 transistors greatly 
simplifies construction of high-quality FM 
tuner. IC includes circuits for converting IF out- 
put signal to lower frequency for driving phase- 
locked loop of demodulator. Use of varicap 



front end permits switched or continuous tun- 
ing with 100K Helipot or with switched preset 
100K pots connected between +12 V and 
ground. Tuning controls can be remotely lo- 
cated. After 60 dB of amplification in NE563 IC, 
signal passes through ceramic filter F (Vernitron 



FM-4 or Toko CFS) before being fed back 
through C 5 to IC for mixing with crystal-con- 
trolled 9.8-MHz local oscillator. Article covers 
construction and operation of tuner in detail. — 
J. B. Dance, High-Quality F.M. Tuner, Wireless 
World, March 1975, p 111-113. 



383 



384 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




™ M 



L3 
L4 



turns no. 16 tinned bus wire, 
W ID, 5/8" long, tapped at 2V; 
turns 

3 turns no. 16 tinned bus wire, 
>k" ID, 3/8" long, tapped V 2 turn 
from C13 end 

4 turns no. 22 enamelled wire, 
closewound, W ID 

25 turns no. 28, closewound on 
body of 100k, 1-watt resistor 



RFC6 
RFC9 



RFC7 
RFC8 



5 turns no. 16 tinned bus wire, 
5/16" ID, W long 



4 Amidon ferrite beads on Vs" 
length of no. 24 wire 



3 Amidon ferrite beads on V2" 
length of no. 24 wire 



18-MHz crystal ground for 20-pF 
load capacitance 



144-MHz FM TRANSMITTER— Low-power cir- 
cuit was developed for use with double-conver- 
sion continuous-tuning FM receiver suitable for 
either fixed or mobile communication on 2- 
meter amateur band. Q4-Q6 are part of RCA 
CA3018 IC. Power outpul: with 12-V supply is 
about 1.5 W. Two crystals; are selected by slide 
switch; tuning can be compromised to use crys- 
tals whose 2-meter outputs are 1 MHz apart. 
Article also gives all circuits for receiver. — J. H. 
Ellison, Compact Package for Two-Meter FM, 
Ham Radio, Jan. 1974, p 36-44. 



MIKE 




FM MODULATOR — Developed to permit FM op- 
eration on AM transceiver. Consists of micro- 
phone preamplifier, driver amplifier, and 8-MHz 
crystal oscillator providing 24-MHz output. 



Audio from modulator drives variable-capaci- 
tance diode D1 (which can be silicon switching 
diode) in oscillator circuit. Adapter feeds AM 
transmitter in which frequency multipliers in- 



crease deviation to about 8.5 kHz. To reduce 
deviation for narrow-band FM, adjust 500K pot 
in preamp. — R. Orozco, Jr., Put That AM Rig on 
FM, 73 Magazine, April 1 976, p 34-35. 



FREQUENCY MODULATION CIRCUITS 



385 



18p" 




* 200p for stereo 



Wife 



lUUnafft 
I 1 



SINGLE-LED TUNING INDICATOR— Circuit 
shown, when driven by IF output of FM tuner, 
permits tuning for maximum brightness of sin- 
gle LED such as 5082-4403. Article gives choice 
of two tuning indicator circuit arrangements 
that can be used with the SBA750 limiting IF 
amplifier and detector IC. Recommended ver- 
sion of tuning indicator uses Plessey SL3046 
five-transistor array with discrete resistors and 
capacitor to drive LED. Arrangement gives very 
clear, sensitive indication of correct tuning 
point to within a few millivolts. — J. A. Skingley, 
Sensitive F.M. Tuning Indicator, Wireless 
World, June 1974, p 173-174. 



2-W 2-METER PHASE-LOCKED FM TRANSMIT- 
TER— Operating frequency of 144-148 MHz is 
generated directly, without using frequency- 
multiplier stages. Oscillator stability is achieved 
by phase-locking oscillator to crystal. Tuning 
range of 143-149 MHz corresponds to varactor 
control voltage of 1-4 V, which maintains 
proper loop gain across entire band. ECL decade 
divider U2 is Plessey SP647 driving Schottky- 
clamped divider U3B to give overall division of 
SO. Phase detector and loop amplifier functions 
are in U4. Pierce crystal oscillator Q3 feeds 
buffer Q4 interface with TTL levels. Microphone 
preamp U5 is slightly overdriven so speech 
waveform is clipped or limited. With phase- 
locked circuit, frequency stability is as good as 
that of crystal used in reference oscillator. Di- 
vide desired operating frequency by 25 to get 
crystal frequency.— A. D. Helfrick, A Phase- 
Locked 2-Meter FM Transmitter, QST, March 
1977, p 37-39. 



EXCEPT AS INOICATED, DECIMAL 
VALUES OF CAPACITANCE ARE 
IN MICROFARADS {jiF); OTHERS 
ARE IN PICOFARADS ( pF OR jijjFI; 
RESISTANCES ARE IN OHMS; 
k -1000 . M>1 000 000 




. . . .47 

WOO . . MYLAR 



C1-C6, incl. - 1,000-pF ceramic feedthrough 

capacitors. 
C7, C8 - 14- to 150-pF ceramic trimmer 

(Arco 424). 
CR2, CR3 - BB105 or Motorola MV839 Var- 

icap diode, 82 pF nominal capacitance, 

73.8- to 90.2-pF total range. 
LI, L3, L7 — 33-ju.H molded inductor (Miller 

9230-56). 
L2 - 1 -1 II turns no. 20 enameled wire, 1 /4- 

inch diameter, 1/2-inch long. 
L4 - 3 turns no. 28 enameled wire through 

ferrite bead. 
L.5 — 2.2-juH molded inductor (Miller 9230- 

28). 
L6 - 1-1/2 turns no. 20 enameled wire, 3/8- 

inch diameter, 1-inch long. 
L8 - 100-mH molded inductor (Miller 9230- 

68). 



??\ '000 ..MYLAR- 

1 Vv\ i-^WV 1(— -j 



Q1 - RCA 2N3866 or Motorola HEP S3008 
transistor. 

Q2 — C3-12, manufactured by Communica- 
tions Transistor Corp., a division of Varian. 
An RCA 2N5913 may be substituted. 

Q3, Q4 - RCA transistor. 

U1 — 5-volt, 1 -ampere fixed positive regulator. 

An LM309K may be substituted. 

U2 — Plessey Semiconductors integrated cir- 
cuit. 

U3 - Signetics 82S90 or National 
DM73LS196 integrated circuit. 

U4 — Motorola MC4044 integrated circuit. 

U5 - RCA CA3130 integrated circuit. 

Y1 - Overtone Crystal, 5.76-5.92 MHz, Inter- 
national Crystal Mfg. Co. Type GP. Crystal 
frequency is discussed in the text. 



386 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 







+ , 












741 


IC, 5^. 




2!°i f 


v sense*-^" 












(w 








I '•< 1 1 















' R 
!lk 



Vre<0 




-soon 



TUNING NULL INDICATOR— Uses standard 
left-zero meter as tuning indicator connected in 
basic opamp AC voltmeter configuration using 
IC,, with reference buffered by opamp IC 2 . DC 
output voltage of tuner is compared with non- 
zero reference voltage; as these voltages ap- 
proach each other during tuning, meter pointer 
moves toward zero, and abruptly reverses di- 
rection as tuning null point is passed. Diode D, 
protects meter from overload. Use any low- 
leakage diodes for bridge. — A. S. Holden, Sen- 
sitive Null Indicator, Wireless World, Oct. 1974, 
p381. 



Final I.F. 



C, 



ADD-ON FM DETECTOR— Suitable for any com- 
munication receiver. Other IF values can be han- 
dled by changing values of L and C. Connecting 
C 2 to pin 10 instead of pin 9 may improve per- 
formance. Circuit is easy to construct and align; 
adjust slug-tuned coil for maximum recovered 
audio when receiving FM signal. — I. Math, 
Math's Notes, CO, April 1975, p 37-38 and 62. 



455 kHz 

2Mhz 

4.5 Mhz 

5.5 Mhz 

10.7 Mhz 



680 pF 3 pF .005 
300 pF 3 pF .005 
120 pF 3pF .003 
100 pF 3pF .003 
lOOpF 4.7 pF .01 



22K 135-240 /iHy 

22 K 16-30 ^Hy 

22K 7-14 /iHy 

22K 5-8 iMy 

3.9K 1.5-3 /iHy 



Note: 

ICi can be 
Signetics N5111A or 
Motorola MC1357P 



+12v. 

@25ma 

approx. 




To A.M. To 

detector volume 
control 



| l 2 LOCK RANGE ADJUSTMENT 
0.01//F 



LOOP FILTER 
O.OVF 



FM INPUT 

f c = 5MHz O 
f m = 1kHz 

BIAS FILTER 




ANALOG OUT 
O 1kHz 

POST DETECTION 
FILTER 



f D 5MHz 
FREQUENCY SET CAP 



FM DEMODULATOR— Uses Signetics NE564 
PLL having postdetection processor, operating 
from 5-V supply. Conversion gain is low so fre- 
quency deviation in input signal should be at 
least 1%. — "Signetics Analog Data Manual," 
Signetics, Sunnyvale, CA, 1977, p 828-830. 



FREQUENCY MODULATION CIRCUITS 



387 




2-METER IC RF AMPLIFIER— High-gain double 
compound amplifier using RCA CA3102E has 
low noise, excellent stability, and only two 
tuned circuits. Ideal for 2-meter FM RF stage, 
but can be used from DC up to 500 MHz by 
changing tuned circuits. Article covers con- 
struction, with emphasis on proper shielding. — 
B. Hoisington, Two High Gain RF Stages in One 
IC for Two Meter FM, 73 Magazine, May 1974, 
p 47-50 and 52. 



+9V 



FM DEMODULATOR— Uses RCA CA3046 
IC IF amplifier connected as highly linear volt- 
age-controlled oscillator, in phase-locked loop 
configuration capable of handling 10.7-MHz am- 
plitude-limited FM input as FM demodulator. 
Output AF signal is about 20 mV for 75-kHz de- 
viation. FET serves as synchronous-chopper 
type of phase-sensitive detector. — J. L. Linsley 
Hood, Linear Voltage Controlled Oscillator, 
Wireless World, Nov. 1973, p 567-569. 




modulation 
out 




OEMOO 

O outwjt 



FINE TUNE 



LINEAR FM DEMODULATOR— Exar XR-2212 
precision PLL IC provides linear demodulation 
for both narrow-band and wideband FM sig- 
nals. Article gives circuit design procedure. 
With +12 V supply voltage and 67-kHz carrier 
frequency having ±5 kHz frequency deviation, 
R is 18K fixed resistor in series with 5K pot. C 
(between pins 13 and 14) is 746 pF, R, is 89.3K, 
C, is 186 pF. R F is 100K, and R c is 80.6K. These 
values give ±4 V P output swing. All values ex- 
cept R can be rounded off to nearest standard 
value.— "Phase-Locked Loop Data Book," Exar 
Integrated Systems, Sunnyvale, CA, 1978, p 35- 
40. 



388 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



"1 



10K 




IOK 

-vw-o 

OEMOO 
OUTPUT 



^CARRIIRPBESENCF 
^OUTPUT 



DEMODULATOR WITH CARRIER DETECT— 
Exar XR-567 PLL system is used with XR-21 5 FM 
demodulator to detect presence of carrier signal 
in narrow-band FM demodulation applications 
where bandwidth is less than 10% of carrier fre- 
quency- Output of XR-567 is used to turn off FM 
demodulator when no carrier is present, giving 
squelch action. Circuit will detect presence of 
carrier up to 500 kHz.— "Phase-Locked Loop 
Data Book," Exar Integrated Systems, Sunny- 
vale, CA, 1978, p 41-48. 



RF INPUT 

(225 MHz, 50 U) 





U_ / I F OUTPUT 

" N (21.4 MHz, 50 U) 



C16f f »» Vdc 
^ *r*C19 
tig; "i" fS' 

t ~ i/- / LP INPUT 



5fe C18 
C17 



(246.4 MHz, 50 U) 



Vdc 



CI — 8.2 pF Ceramic disc capacitor 

C2 - 43 pF Dipped, silvered mica capacitor 

C3 — 0.2 pF Ceramic tubular capacitor 

C4 - 12 pF Ceramic disc capacitor 

C5 — 15 pF Dipped, silvered mica capacitor 

C6, C7, C8. C9, C10 

C16 — 220 pF Ceramic disc capacitor 

C1 1 — 10 pF Dipped, silvered mica capacitor 

C12 - 0.47 pF Ceramic tubular capacitor 

C13 - 3.6 pF Ceramic tubular capacitor 

C14 — 8—60 pF Mica compression trimmer, Arco 404 
C15, C19 - 0.01 /JF Ceramic disc capacitor 

C17, C18 - 3 pF Dipped, silvered mica capacitor 



020 - 24 pF 



Dipped, silvered mica capacitor 



R1 - 300 kilohm, 1/4 W carbon resistor 

R2 - 27 kilohm, 1/4 W carbon resistor 

R3 - 62 kilohm, 1/4 W carbon resistor 

R4 - 56 kilohm, 1/4 W carbon resistor 

R5 - 220 ohm, 1/4 W carbon resistor 

R6 - 910 ohm, 1/4 W carbon resistor 

L1 - 2-1/2 turns no. 20 enameled wire on 9/32" plastic form with brass slug (70 nH) 

L2, L4 - 2-1/6 turns no 20 enameled wire on 9/32" plastic form with brass slug (60 nH) 

L3 - 1-5/6 turns no. 20 enameled wire on 9/32" plastic form with brass slug, tapped 1/2 turn from ground (55 nH) 

L5 — 2-1/2 turns no. 20 enameled wire on 9/32" plastic form with brass slug, tapped 2/3 turn from ground (70 nH) 

Q1 -3N201 MOSFET 

Q2 -2N5486 JFET 

T1 — Primary = 18 turns no. 24 enameled wire on T44-6 Micrometals toroid core 

Secondary = 4 turns no. 24 enameled wire twisted around last 4 turns of ground end of primary 



225-MHz FRONT END— RF stage, mixer, and 
tuned circuits are designed for use in FM com- 
munication receiver having local oscillator 
input of 246.4 MHz, for IF of 21.4 MHz. Supply 



voltage is 12.5 V. Spurious-response rejection 
is 100 dB, image rejection is 97 dB, and noise 
figure is 12 dB. — J. Hatchett and B. Morgan, 



"Economical 225 MHz Receiver Front End Em- 
ploys FETs," Motorola, Phoenix, AZ, 1978, EB- 
22. 



FREQUENCY MODULATION CIRCUITS 



389 



+v 
o 



MOO. 
FREQ. 
ADJ. 



+V 

O 



RELAY OUTPUT 



8 6 

566 



- if 




=■ ~- DEVIATION 

ADJUST 

LOW-PASS FILTER OR SINE CONVERTER 
MAY BE INSERTED HERE IF SINUSOIDAL 
MODULATION IS REQUIRED 



As/ 



0.5 MHz WITH 100% DEVIATION— Carrier fre- 
quency under 0.5 MHz Is generated by 566 func- 
tion generator at right, for modulation by other 
566 connected as triangle generator whose out- 



put is boosted by 531 opamp to give deviations 
up to ± 100% of carrier frequency. Capacitors C, 
control frequency range of each function gen- 
erator.— "Signetics Analog Data Manual," Sig- 
netics, Sunnyvale, CA, 1977, p 852-854. 




TO RECEIVER 
AUDIO STAGE 
(SEE TEXT] 



CARRIER-OPERATED RELAY— Relay is ener- 
gized when carrier is present in FM receiver, to 
activate transmitter for repeater applications or 
turn on tape recorders, alarms, or other devices. 
Will work with either solid-state or tube-type 
receivers. Inverting (minus) input of opamp is 
connected directly to collector of audio preamp 
transistor or any other point having voltage 
change between signal and no signal. If voltage 
change is in wrong direction, reverse leads to 
opamp input. Use 1K pot to set reference volt- 
age so relay trips reliably on incoming signal. 
Relay can be reed-type drawing less than 75 
mA.— S. Uhrig, The 5 Minute COR, 73 Maga- 
zine, Dec. 1976, p 152-153. 



-0 + 12V 




#ferrite bead 



-Oa.'.c. 



VARICAP TUNER— Uses silicon variable-capac- 
itance diodes to provide voltage tuning over FM 
band of 87.5 to 108 MHz. Article covers con- 
struction and adjustment and gives circuit of 



stable noise-free regulated power supply that Resistors R can be any value between 1 00K and 

also provides required DC tuning voltage of 2 to 1 megohm.-L. Nelson-Jones, FM. Tuner De- 

30 V. All six varicap diodes are Siemens BB103 sign-Two Years Later, W/re/ess World, June 

of same color selection (all green or all blue). 1973, p 271-275. 



390 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




DEMODULATED 
I bK OUTPUT 



001 uf 
~T~ IDE EMPHASISI 



"^rf 



•TN- 1 /T7 



x^ — T c 

I 01 



65-130 MHz DIODE RECEIVER— Tunable ver- 
sion of basic crystal detector is useful for FM 
broadcast work and for checking output of fre- 
quency multiplier. L2 is; 5 turns center-tapped 
No. 12 copper wire air-wound to 5/8-inch di- 
ameter and 1-inch length. CI is 30-pF miniature 
tuning capacitor. — B. Hoisington, Tuned Diode 
VHF Receivers, 73 Magazine, Dec. 1974, p 81- 
84. 



DEMODULATOR— Uses Exar XR-215 PLL IC 
connected for frequency-selective demodula- 
tion of FM signals. Value of C depends on car- 
rier frequency. C, determines selectivity; for 1- 
10 MHz, range of C, is 10-30 times C . For op- 



coupling CAPACITOR 

BYPASS CAPACITOR 



eration below 5 MHz, R x can be opened; above 
5 MHz, use about 750 ohms. — "Phase-Locked 
Loop Data Book," Exar Integrated Systems, 
Sunnyvale, CA, 1978, p 21-28. 



0+15V 



Multiplex 
input R, 



o-vw-t-^vw 

5k6 9k1 




STEREO DECODER — Improved circuit for FM 
tuner uses active filters to eliminate subcarrier 
harmonics as well as birdlike interference 
sounds (birdies) experienced under certain con- 
ditions. Stereo reception normally involves de- 
modulation of stereo channel at 38 kHz by 
square-wave switching, a process that also de- 
modulates signals around odd harmonics of 38 
kHz. The first two of these, at 1 14 and 190 kHz, 



can produce audible signals from adjacent 
channels at 100 and 200 kHz away from wanted 
station. Resulting interference, centered on 14 
kHz and 10 kHz, sounds like high-pitched twit- 
tering sounds of birds. Tr, serves as active filter 
for suppressing these sounds. This is followed 
by phase-locked loop type of IC decoder, oper- 
ation of which is described in article that also 
gives complete circuit and construction details 



for entire FM tuner. All transistors are BC109 or 
equivalent. LED is 5082-4403. Tr, has roll-off re- 
sponse at 18 dB per octave above 53 kHz, while 
active filters Tr 2 and Tr 3 remove harmonics of 38 
kHz from outputs. — J. A. Skingley and N. C. 
Thompson, Novel Stereo F.M. Tuner, Wireless 
World, Part 2— May 1974, p 124-129 (Part 1— 
April 1974, p 58-62). 



FREQUENCY MODULATION CIRCUITS 



391 




MOSFET RF STAGE— Changing 6AK5 tube to 
3N204 dual-gate MOSFET improves sensitivity 
and lowers noise in older VHF FM communica- 
tion receiver using tubes. Break off center 
grounding pin of tube socket and cut wires sol- 
dered to pin, then connect transistor circuit to 
tube socket as shown. Replace original resistor 
going to pin 6 with 120K and run 37K resistor 
from pin 6 to ground. Move antenna input lead 
to top of RF input coil, and remove 6-V filament 
wiring from socket. If tube filaments were in se- 
ries, replace 6AK5 filament with 36-ohm 2-W re- 
sistor. Conversion increases sensitivity to 0.3 
tiV for 20-dB quieting.— H. Meyer, How to Im- 
prove Receiver Performance of Vacuum-Tube 
VHF-FM Equipment, Ham Radio, Oct. 1976, p 
52-53. 



TWIN-LED TUNING INDICATOR— Provides 
maximum sensitivity at correct tuning point 
and indicates direction of mistuning. Both 
lamps are in feedback loop of one opamp, con- 
nected to serve as highly sensitive null detector. 
When set is tuned correctly, output of this 
opamp is at midpoint of supply voltage and nei- 
ther LED is lit. Circuit is used with RCA CA3089 
IF chip in which AFC output is a current. Capac- 
itor across first 741 opamp removes modulation 
components from this input. — M. G. Smart, 
F.M. Tuning Indicators, Wire/ess World, Dec. 
1974, p 497. 



luon 
r— 1— AVv— 1— > 




a. f.c. voltage 
or current 



a.-f.c. reference 




loop narrow-band FM demodulator. With value version techniques involving phase-locked 

shown for C, circuit is suitable for IF value loop.— P. Hawker, Synchronous Detection in 

NARROW-BAND DEMODULATOR— Low-cost around 470 kHz. Article covers advantages of Radio Reception, Wireless World, Nov. 1972, p 

TTL ICs are connected to form phase-locked synchronous detection and various direct con- 525-528. 



392 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+10 VOLTS 



DEM 
FM 



510 pF 



510 pF 



:;4.7, 



10K 



4.7K 




0tt\f 



+2« VOLTS 



.0181* 



BACKGROUND 
MUSIC (SCA) 



ri 



SCA DEMODULATOR— VCO of NE565 PLL is set 
at 67 kHz and is locked in by incoming 67-kHz 
subsidiary-carrier component used for trans- 
mitting uninterrupted commercial background 
music by FM broadcast stations. Circuit demo- 
dulates FM sidebands and applies them to 
audio input of commercial sound system 
through suitable filter. SK pot is used to lock 
VCO exactly on frequency. Frequency response 
extends up to 7000 Hz. — E. M. Noll, "Linear IC 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 1974, p 212-213. 



STEREO DECODER— Single Sprague ULN- 
2122A IC is driven by composite signal derived 
at output of standard FM detector, to give orig- 
inal left- and right-channel audio signals for 
driving audio amplifiers of FM stereo receiver. — 
E. M. Noll, "Linear IC Principles, Experiments, 
and Projects," Howard W. Sams, Indianapolis, 
IN, 1974, p 263-266. 



INPUT 
\ 



^K^r 



200mvrms COMPOSITE 
LEFT ONLY, 1 kHz 
10* PILOT 
75|is DE-EMPHASIS 



MILLER 
1361 

SmH 




RIGHT 
' OUTPUT 



:E0.02|if 



* ADJUST FOR BEST SEPARATION 



T 2 
26.8 VCT 



tc 




I 25V 




. SPKR 



CAPACITOR VALUES IN PF 
RESISTOR VALUES IN SI 
•SELECT FOR CARRIER FREQ. 

<o C2 C13 

200 kHi 1000 300 
100 kHz 3900 620 

CARRIER-SYSTEM RECEIVER— Used to detect, 
amplify, limit, and demodulate FM carrier mod- 



01A-Q1E-LM3046 



W to remote loudspeaker. Can be plugged into 
any AC outlet on same side of distribution trans- 
former. Carrier signal is taken from line by tuned 
transformer T, . Output of two-stage limiter am- 
plifier Q1 A-Q1 D is applied directly to mute peak 
detector D1-Q2-C7. Limiter output is reduced to 
ulated with audio program, for feeding up to 2.5 IV P-P for driving National LM565CN PLL de- 



tector which operates as narrow-band tracking 
filter for input signal and provides low-distor- 
tion demodulated audio output. Mute circuit 
quiets receiver in absence of carrier. — J. Sher- 
win, N. Sevastopoulos, and T. Regan, "FM Re- 
mote Speaker System," National Semiconduc- 
tor, Santa Clara, CA, 1975, AN-146. 



FREQUENCY MODULATION CIRCUITS 



393 



SIGNAL INPUT 




ALL RES I STANCE VALUES ARE IN OHMS 
* L TUNES WITH 100 pF (0 AT 10.7 MHz 



SINGLE-TUNED DETECTOR— RCA CA3089E IC 
serves as communication receiver subsystem 
providing three-stage FM IF amplifierllimiter 
channel, with signal-level detectors for each 
stage, and quadrature detector that can be used 
with single-tuned detector coil. Detector also 
supplies drive to AFC amplifier whose output 
can be used to hold local oscillator on correct 
frequency. Level-detector stages supply signal 
for tuning meter. Values shown are for 10.7- 
MHz IF.— E. M. Noll, "Linear IC Principles, Ex- 
periments, and Projects," Howard W. Sams, In- 
dianapolis, IN, 1974, 347-349. 



150 |lA Jr 
FULL SCALE 



QUADRATURE DEMODULATOR— Quadrature 
coil associated with balanced-mixer demodu- 
lation system is connected to pin 6 of National 
LM373 IC, and output signal is taken from pin 7. 
Good output is obtained with only ±5 kHz de- 
viation at either 455 kHz or 10.7 MHz. Can be 
operated as wideband or narrow-band circuit 
by choosing appropriate interstage and output 
LC and RC components. — E. M. Noll, "Linear IC 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 1974, p 350-351. 




BANDPASS 
FILTER 



RF INPUT y « ) [■ 



I CSvL 

/77 /SOOpF— I— 



o 



■ $AFC OUTPUT 




_ ^ STEREO 

T y output 

— ' — r 



IOO KHi 
LOW-PASS FILTER 



I MONO OUTPUT 



CI3 APPROX 

O.lliF 560pF 

rfl (USED ONLT 
WITH XTAL) 



■ 75vSEC 
.OIpF' ^ DE-EMPHISIS 

rh 



Pa IF AND DEMODULATOR— Signetics 
NE563B IC (in dashed lines) serves as complete 
IF amplifier and demodulator for FM broadcast 
receiver. Circuit uses downcenversion from 



10.7 MHz to 900 kHz, where phase detector op- 
erates. Ceramic bandpass filter provides IF se- 
lectivity at 10.7 MHz. X1 can be 9.8-MHz ceramic 



resonator, LC network, crystal, or capacitor. — 
H. Olson, FM Detectors, Ham Radio, June 1976. 
p 22-29. 



394 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




0.5 MHz WITH 20% DEVIATION— One 566 func- 
tion generator serves for generating relatively 
low-frequency carrier (center frequency less 
than 0.5 MHz), and other 566 serves as modu- 
lator producing triangle output with frequency 
determined by C,. Combination is suitable for 
deviations up to ±20% of carrier frequency. — 
"Signetics Analog Data Manual," Signetics, 
Sunnyvale, CA, 1977, p 852-853. 



LOW-PASS FILTER OR 
SINE CONVERTER MAY 
BE INSERTED HERE 
IF SINUSOIDAL MODULATION 
IS REQUIRED 



FM DETECTOR — Single IC can be added to any 
receiver not having FM detector. Moving C 2 
from pin 9 to pin 10 gives higher audio output. 
Receivers having less than 5 kHz IF bandwidth 
can be broadened by stagger-tuning IF strip 
slightly to improve audio clarity. Adjust tuned 
circuit of detector for maximum recovered 
audio. — I. Math, Math's Notes, CO, June 1972, 
p 49-51 and 80. 




I.F. 


Cl (pf) 


Cz(pf) 


L|I»H) 


10.7mHz 


120 


4.7 


1.5-3 


4.5mHz 


120 


3.0 


7-14 


2mHz 


300 


3.0 


16-30 


455kHz 


650 


3.0 


135-240 




CARRIER-SYSTEM TRANSMITTER— Used to 
convert audio program material into FM format 
for coupling to standard power lines. Modu- 
lated FM signal can be detected at any other 
outlet on same side of distribution transformer, 
for demodulation and drive of loudspeaker. 



Input permits combining stereo signals for 
mono transmission to single remote loud- 
speaker. Uses National LM566CN VCO. Fre- 
quency response is 20-20,000 Hz, and total har- 
monic distortion is under 0.5% With 120/240 V 
power lines, system operates equally well with 



receiver on either side of line. Transmitter input 
can be taken from monitor or tape output jack 
of audio system. — J. Sherwin, N. Sevastopou- 
los, and T. Regan, "FM Remote Speaker Sys- 
tem," National Semiconductor, Santa Clara, 
CA, 1975, AN-146. 



FREQUENCY MODULATION CIRCUITS 



395 



10k 
^M »»out 




AUDIO 
OUTPUT 
-f — wv f 



TRANSISTOR-PUMP DISCRIMINATOR— Used 
with 10.7-MHz IF strip of high-quality FM tuner 
built from discrete components. Circuit is 



placed between last IF stage and stereo de- 
coder. — W. Anderson, F. M. Discriminator, 
Wire/ess World, April 1976, p 63. 




CRYSTAL DISCRIMINATOR— Inexpensive 

third-overtone CB crystal used at 9-MHz fun- 
damental serves as high-performance discrim- 
inator for VHF FM receiver. Adjust C3 for zero 
voltage with unmodulated carrier at or near 
center frequency. Adjust C1 and C2 with AF sine 
wave applied to FM signal generator, using CRO 
to check distortion of recovered sine wave. With 
1 V P-P IF signal at 9 MHz and S-kHz deviation, 
recovered audio will be about 1 V P-P at lower 
audio frequencies. Good limhter is required 
ahead of discriminator for AM rejection. — G. K. 
Shubert, Crystal Discriminator for VHF FM, 
Ham Radio, Oct. 1975, p 67-69. 




6 -12V 

LED TUNING INDICATOR— One LED is mounted 
at each end of tuning scale. Tuning pointer is 
moved away from whichever LED is on, to dead 
spot at which both are off, to obtain correct tun- 
ing point. Advantages of lights-off tuning in- 
clude minimum current drain and indication of 



tuner earth 



even very slight mistuning by having one light 
come on even slightly. Adjust VR, to give wide 
enough dead spot so LEDs do not flicker on loud 
speech or music— H. Hodgson, Simpler F.M. 
Tuning Indicator, Wire/ess World, Sept. 1975, p 
413. 




21-75 MHz DIODE RECEIVER— Covers 6-meter 
band and most 2-meter FM receiver oscillators 
near 45 MHz. Circuit is essentially that of crystal 
detector. Jack J3 gives AF output, and J2 gives 
DC output for meter.— B. Hoisington, Tuned 
Diode VHF Receivers, 73 Magazine, Dec. 1974, 
p 81-84. 



I Rf 

AMP 




MIXER 


I 
















VFO 

OR 

FIXED 




DEVIATION METER— Uses simple crystal oscil- 
lator combined with fixed or tunable FM re- 
ceiver and CRO to show carrier shift on either 
side of center frequency. Vertical amplifier of 



27«.F 



: : lO.oooil 




TM20«iF S2.7K 



CRO should be direct-coupled. To calibrate, 
tune oscillator either 10 or 15 kHz above or 
below second oscillator of receiver, and cali- 
brate screen of CRO accordingly. One calibra- 



o 



A-NORMAL 
B-CALIBRATE 



YI-CRYSTAL 10-15 KHz 
FROM SEC. OSC. FREQ. 



tion oscillator is sufficient since transmitter 
usually deviates equally well both ways. — V. 
Epp, FM Deviation Meters, 73 Magazine, March 
1973, p 81-83. 



396 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




O TRACKING 
RANGE 



ANALOG PLL AS FM DEMODULATOR— Upper 
frequency limit of about 50 MHz for NES62 and 
other monolithic analog phase-locked loops 
complicates construction of FM telemetry re- 
ceivers that directly demodulate standard 88- 
108 MHz FM broadcast signals. Circuit shown 
solves problem, with only small amount of sig- 
nal preconditioning, by first converting RF car- 
rier to 10.7 MHz with conventional superhetero- 
dyne front end, then applying signal to phase 
detector of PLL with VCO set to run free at 10.7 
MHz. Input sensitivity is less than 30 /tV, and 
audio output is greater than 100 mV. — E. Mur- 
thi. Monolithic Phase-Locked Loops — Analogs 
Do All the Work of Digitals, and Much More, 
EDN Magazine, Sept. 5, 1977, p 59-64. 



12V 



OPAMP DRIVE FOR LED TUNING LAMPS— 
Opamp with 100K feedback resistor gives gain 
of 10 as optimum compromise for driving two 
LED tuning indicators in FM receiver. — R. D. 
Post, F.M. Tuning Indicator, Wireless World, 
May 1975, p 220. 




♦ 12V 

vcco— 



IF INPUT , 

FROM TUNER 




CERAMIC FILTERS 
I 10 7 U 10 7 



-J- o.m 



-4-0.01 



16 1 

16 2 

14 3 

LM 

" 3089 4 

12 6 

II 6 

10 7 

9 8 



"1 

-j0.01>33 




AFC 

TO TUNER 



— 3nF 

yioopF 



RIGHT 
OUTPUT 



LEFT 
OUTPUT 

i, 



STEREO 

INDICATOR 

LAMP 

-M- 



©CEN 
TUN 
600 



NTER 

IE 
50 



LM 
1310 



J.22I 



^ 19kHz 

'monitor 



zn 



0.033 OSC 
ADJ 



r<5k 
1 



15.6V • 7mV/kHi) 

IF AND STEREO DEMODULATOR— National 
LM3089 IC and LM1310 PLL FM stereo demod- 
ulator provide all circuits required between FM 
tuner and inputs to power amplifiers of stereo 
receiver. Use of 10.7-MHz ceramic filters elim- 



inates all but one IF alignment step. AFC output 
from pin 7 of IF strip drives center-tune meter. 
Wide bandwidth of detector and audio stage in 
IF strip is more than adequate for stereo receiv- 
ers. Audio stage can be muted by input voltage 



to pin 5. Demodulator IC includes automatic 
stereo/monaural switching and 100-mA stereo 
indicator lamp driver. Optional 300-pF capacitor 
on pin 6 of LM3089 can be used to limit band- 
width. — "Audio Handbook," National Semi- 
conductor, Santa Clara, CA, 1977, p 3-18-3-23. 



FREQUENCY MODULATION CIRCUITS 



397 



frOm 

discriminator 

output 



from a.f.c. 
reference — #»» 
potential 




AFC AMPLIFIER— Simple DC amplifier can be 
added to AFC circuit of FM tuner to eliminate 
tuning errors over entire lock-in range. — J. S. 
Wilson, Improved A.F.C. for F.M. Tuners, Wire- 
less World, July 1974, p 239. 



VT~V 

? 60J1 ?&Oii 



1 



gndJ3 



DEMODULATED 
10K OUTPUT 




A 1 *_J* 

*30pF ■ a IOM u - 
/t , T cHVS 



)MH{ 
CBYSTAL 
(FUNDAMENTAL 
MODE) 



D 2 

1N4003 






D, 
1N4003 



200mf 
10 «. 



R, 
3.3 K 



Spotlight I * U7 



R 2 
39 K 



5600 mf 
25 v. 



I 6 «d.c. 

T> son 



S 



2N3646 

or RCA 

SK3019 



Q^/ orR 



< Allied 



j f- control 
-> T154-CC 



2N3053 

RCA 

SK3024 



JXtt 

Switch 

Squelch ^_ 
Tube *" 
cathode 
Transceiver 
ground 



CALL ALERT — Developed to trigger relay when 
signal arrives at squelch tube in GE Progress 
Line 2-meter FM receiver. Relay is held ener- 
gized about 2 s, determined by C,-R„ then de- 
energized for at least 25 s. Used for flashing red 
spotlight in room that is too noisy for hearing 
bell or buzzer. Circuit is easily adapted for any 
other FM receiver having squelch stage. Control 
circuit responds to small change in voltage at 
cathode of squelch tube. With no carrier pres- 
ent, tube conducts and places positive voltage 
at face of Q„ making it conduct and turn off Cv 
When carrier arrives, Q, restores bias to Q2, 
turning on relay. Connection to push-to-talk 
switch keeps lamp from flashing during trans- 
mission.— L. Waggoner, The WAOQPM "Call 
Alert," CO, May 1971, p 48-49. 



CRYSTAL FM DETECTOR— Exar XR-215 PLL IC 
is operated as crystal-controlled phase-locked 
loop by using crystal in place of conventional 
timing capacitor. Crystal should be operated in 
fundamental mode. Typical pull-in range is ±1 
kHz at 10 MHz. — "Phase-Locked Loop Data 
Book," Exar Integrated Systems, Sunnyvale, 
CA, 1978, p 21-28. 



25 WAT, 
BLY89A IZnH ^ OUTPUT 



BLYB7A 2 3 „„ , 0nH 

h rvw\liirrYr\ 

te 




€71 



^r^ 



X^og 5voc 



VHF POWER AMPLIFIER— Three-stage 25-W 
225-MHz power amplifier module for FM appli- 
cations uses three Amperex power transistors. 
Input and output are 50 ohms. With 100-mW 



input signal, output is 25 W. Four capacitive di- 
viders serve for input, output, and interstage 
matching. Collectors are shunt-fed. Three de- 
coupling networks prevent self-oscillation. Am- 



plifier can withstand output mismatches as 
high as 50:1 without damage. — E. Noll, VHF/ 
UHF Single-Frequency Conversion, Ham Radio, 
April 1975, p 62-67. 



398 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




C1 - 10 pF 
C2, C3 - ISpF 
C5 - 68 pF 
C6 - 18 pF 
C7, C9 - 12 pF 
C8, C10 - 20 pF 
C17 - 82 pF 



Dipped Silvered 
Mica, El-Menco 
Case DM10 



C1 1, 14 — .01 nF Ceramic Disc 
CI 2, 15 - 220 pF Ceramic Disc 
C13, 16 — 5 /UF, 25 V, Aluminum 

Electrolytic 
C4 - 3-35 pF Trimmer, ARCO NO. 403 
L1 - 5 T NO. 20 AWG Wire, Wound on R2 (50 

nH| 
L2 - 1.5 T NO. 20 AWG Wire, 0.25-ln. I.D. (30 

nH) with Ferroxcube 5659065/3B Ferrite 

Bead 



L3 - 2 T NO. 20 AWG Wire, Wound on R3 (35 

nH) 
L4, 5 - 2 T NO. 18 AWG Wire, 0.25-ln. I.D. 

(44 nH) 
L6 - 3.5 T NO. 18 AWG Wire, 0.25-ln. I.D. (90 

nH) 
R1 - 100 Ohm, 1/4 W, ±10% Carbon Resistor 
R2 - 820 Ohm, 1/2 W, ±10% Carbon Resistor 
R3 - 330 Ohm, 1 W, ±10% Carbon Resistor 
R4 — 22 Ohm, 1/4 W, ±10% Carbon Resistor 
RFC1, 2 - Ferroxcube VK200 19/4B Choke 

Z1 - Microstrip Line, 2200 X 62 Mils 
Z2 - Microstrip Line, 1200 X 62 Mils 
Z3 - Microstrip Line, 1000 X 62 Mils 
Z4 - Microstrip Line, 1600 X 62 Mils 
Board — G10 Epoxy-Glass, e r = 5, t = 62 Mils 
1 02. Copper 



225-MHz 13-W AMPLIFIER— Suitable for use in 
FM transmitters for 220-225 MHz amateur 
radio band. Bandwidth is about 10 MHz for ±0.5 
dB. Low-pass filter provides about 60-dB atten- 



uation of second harmonic. Microstrip match- 
ing network simplifies construction. Supply 
voltage is 12.5 V. — I. Hatchett and T. Sallet, 



"13-Watt Microstrip Amplifier for 220-225 MHz 
Operation," Motorola, Phoenix, AZ, 1975, AN- 
728, p 3. 



CHAPTER 35 

Frequency Multiplier Circuits 



Emphasis is on frequency doubters, but includes circuits providing multiplying 
factors up to 10 for sine, square, and other waveforms in audio range and in 
RF systems extending well above 400 MHz. 



O +12V 



SIMPLE DOUBLER— Performance is good up to 
about 10 kHz. R 2 is adjusted to set FET just at 
cutoff under no-signal conditions, to give op- 
eration in square-law region. With R, correctly 
adjusted, using scope or third harmonic distor- 
tion monitor to obtain minimal distortion, har- 
monic content of output can be made to ap- 
proach that of sine-wave input. Article gives 
design equations.— R. Williams and J. Dunne, 
Frequency Doubler, Wireless World, Dec. 1975, 
P575. 




O "6 to 10V 



*12DC 
O 




►_1_100 U F 

25 VOC 



100 

— vw- 



"=r 15 VDC 

MAX 



C2 
^100^F 
15 VDC 



I — Vv\ — | 



'3.9KP-3.9K 



MC 1596K 
MC 1496K 




OUTPUT 



— o 



LOW-FREQUENCY DOUBLER— Signetics bal- 
anced modulator-demodulator transistor array 
is connected much like phase detector circuit. 
Output contains sum component which is twice 
frequency of input signal because same input 
signal frequency goes to both sections of bal- 
anced modulator. — Signetics Analog Data 
Manual," Signetics, Sunnyvale, CA, 1977, p 758. 



VOC 



399 



400 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+12V 




OUTPUT 



SQUARER — Simple tunnel-diode circuit dou- 
bles frequency efficiently without use of tuned 
circuits. Fundamental and other harmonics of 
input are at least 30 dB below level of frequency- 
doubled output. Circuit operates from DC to 
upper frequency limit of opamp used. Adjust R 2 
so diode current is at peak of its bias current, to 
eliminate offset at amplifier output. — R. Kin- 
caid. Squaring Circuit Makes Efficient Fre- 
quency Doubler, EDNIEEE Magazine, Aug. 15, 
1971, p 45. 




B 
i 

C 

COUNTER 
(Ml D 



74154 



T^ 



743u\>— '< 



$ 



M 

10 
12 
16 



TYPICAL 
COUNTER 

7490 
7492 
7493 



USABLE 
74154 OUTPUTS 

1.3,5,7,9 

1.3.5.9.11.13 

1.3.5.7.9,11,13,15 



MULTIPLES OF 2.5 MHz— Three TTL circuits 
provide integral frequency-multiplication ratios 
between 1 and 8. BCD outputs of counter having 
modulus M are fed to inputs of 74154 4-line to 
16-line decoder. As outputs of counter change, 
at rate equal to input frequency divided by 
counter modulus M, each goes low at same 
rate. Output of IMAND gate thus goes high once 
for each input to gate from decoder. If 7490 de- 
cade counter is used and input is 1 MHz, BCD 
outputs of 7490 limit usable outputs of 74154 to 
lines 1, 3, 5, 7, and 9. Since inputs to 74154 
change at 100-kHz rate, output from gate will be 
n x 100 kHz. With input of 25 MHz, output is 
integral multiple of 2.5 MHz. — R. S. Stein, Three 
TTL IC's Provide Frequency Multiplication, EDN 
Magazine, April 5, 1975, p 117 and 119. 



200-400 MHz 

L3.L4 2 turns no. 22 (0.6mm), air core, 1/8' (3mm) diam- 
eter, 1/4" (6.5mm) long 

Q1.Q2 Fairchild 2N5179 recommended but 2N2857, 2N918, 
FMT2060 or equivalent may be substituted 



DOUBLING 200 MHz— Recommended for use 
with VHF/UHF converters having inputs of 180 
to 220 MHz, with 5-10 mW output. Diode in se- 
ries with power supply prevents damage if po- 
larity is reversed. — J. Reisert, VHF/UHF Tech- 
niques, Ham Radio, March 1976, p 44-48. 




■**- 



300 MHz 
_q Output 



i 

^nMOpf 



LI = 1 Turn #18 Wire, 7/32" I.D. 



DOUBLING 150 MHz— Motorola MC1596G bal- 
anced modulator is connected for doubling at 
RF and UHF. With output filtering shown, all 



spurious outputs are at least 20 dB below de- 
sired 300-MHz output. Suppression of spurious 
outputs is poorer for higher input frequencies. 



being only 7 dB down for 400-MHz output, but 
performance is still superior to that of conven- 
tional transistor doubler. — R. Hejhall, "MC1596 
Balanced Modulator," Motorola, Phoenix, AZ, 
1975,AN-531,p10. 



FREQUENCY MULTIPLIER CIRCUITS 



401 



24.5 MHz TO 147 MHz— Uses Q1 as tripler to 
73.5 MHz for frequency-modulated input of 24.5 
MHz, and Q2 as doubler whose output tank is 
tuned to 147 MHz by C6 and L3. Output is about 
200 mW of RF. L1 is 20 turns No. 26 with center 
tap, on 0.5-cm form. L2 is 8 turns No. 22 on 0.8- 
cm form. RFC is 25 turns on 0.5-cm form. Article 
covers troubles likely to be encountered. — B. 
Hoisington, Frequency Multiplication the Easy 
Way, 73 Magazine, Oct. 1973, p 69-71. 




rn 



m 




BROADBAND LOW-FREQUENCY DOUBLER— 
Motorola MC1596G balanced modulator func- 
tions as frequency doubler when same signal is 
injected into both input ports (pins 1 and 8). 
Doubling occurs in audio range and up to about 
1 MHz.— R. Hejhall, "MC1596 Balanced Modu- 
lator," Motorola, Phoenix, AZ, 1975, AN-531, p 
10. 



V+ 
? (+10Vto+15V) 



Frequency 
Multiplier 
Programming 
(As shown, n = 4.) 




f„* 
Output 



•'•-ra 



1 

a 

R,C, 

(As shown, f„ = 50 Hz with 
f , = 60 Hz, n = 4, and M = 6.) 

*4016 CMOS switch sections. 
+ CMOS inverters. 



tR 9 C 2 



I. 



PROGRAMMABLE PLL SYNTHESIZER/MULTI- 
PLIER — Uses programmable timer/counter A, 
as VCO for generating frequencies both above 
and below that of square-wave reference. 



Phase-locked output frequency is not direct 
multiple of reference frequency. 2240 can lock 
on programmable multiple or on subharmonic 
reference. For values shown, phase-locked loop 



is locked through common frequency submul- 
tiple of 10 Hz, to give sampling rate of 10 Hz for 
reference input. — W. G. Jung, "IC Timer Cook- 
book," Howard W. Sams, Indianapolis, IN, 1977, 
p 220-224. 



402 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




o 
© 



©rrjT^i^Tj 



500-5000 Hz SQUARE-WAVE DOUBLER— Cir- 
cuit shows virtually no deviation from 50% duty 
cycle over entire frequency range. Four NOR 
gates in CD4001AE IC form edge detector that 
presents negative pulse to 555 IC timer on both 
rising and falling edges of input square wave, to 
achieve frequency doubling. High-gain 741 
opamp amplifies any difference between DC 
level at timer output and reference equal to half 
of supply voltage, to send correction voltage to 
pin 5 of timer for forcing output to 50% duty 
cycle. — L. P. Kahhan, Frequency Doubler Out- 
puts Square Wave with 50% Duty Cycle, BON 
Magazine, June 5, 1977, p 211-212. 



PUSH-PUSH DOUBLER— Useful in VFO output 
circuits where oscillator operates at half output 
frequency of doubler. Circuit helps reduce os- 
cillator instability during load changes while 
having about same efficiency as straight ampli- 
fier. Uses two sections of RCA CA3028A differ- 
ential amplifier as doubler (U1C is not used). 
Values of tuned circuit depend on frequency, 
which can be up to 120 MHz. — D. DeMaw, Un- 
derstanding Linear ICs, QST, Feb. 1977, p 19-23. 




•— 0+9V 



(5Vp-p at frequency f; 




WIDEBAND DOUBLER— AC-coupled multiplier 
block is connected in squaring mode to provide 
second harmonic of input frequency with no 
tuned circuits. Circuit operates over wide band- 
widths without adjustment. Output is low-dis- 
tortion sine wave; total harmonic distortion is 
typically 1%. Output can be taken from pin 2 or 
14, depending on phase desired. Circuit will 
work with R 7 grounded, but offset adjustment 
can be used to minimize distortion. Maximum 
operating frequency is several megahertz. — W. 
G. Jung, "IC Op-Amp Cookbook," Howard W. 
Sams, Indianapolis, IN, 1974, p 258-259. 



FREQUENCY MULTIPLIER CIRCUITS 



403 



+12v. 



Input f 
o — 



.Imf 



6.8K> ik; 



5K 



rn 
I 1K i.i 

.001 

-If- 



10 8 
2 565 

3 1 9 



47K> .54= 



Output 
lOf 



AMrJ 



±750 
pf 



•1=T= 



4.7K 
-AM 1 



5v. 

Q 



LI 



12 14 11 5 

7490 

10 



,.,<> 2 3 6 7 

1 ^T 7 



PLL MULTIPLIES BY 10— Used with frequency cation by 100. Requires +5 V and +12 V sup- 
counter to measure very low frequencies. Two plies.— H. S. Laidman, Upgrading Inexpensive 
such circuits can be cascaded to give multipli- Counters, CO, Aug. 1975, p 16-22. 



-TL . 




TO- 



"LTLT 



SQUARE-WAVE DO UBLER— Circuit locks onto quency. For high input frequencies, use smaller 
both rise and fall of input square wave, to give capacitance values.— Circuits, 73 Magazine, 
identical square-wave output at doubled fre- April 1977, p 164. 



SQUARE WAVE 

INPUT 

O 



■*o 



D 



r-vW- 

ifL 



1 2 Q 



i — ^ 

L fC>TX> T J 



£ 



uJ 



ICLOCK 



MULTIPLIER/DIVIDER— Choice of values for R 
and C determines multiplication or division fac- 
tor acting on square-wave input frequency. Out- 
put of 4013 flip-flop sets gates of 4011 to steer 
input clock pulse of RCA CD4047AE mono 
MVBR to proper inputs. When rising edge of 
input triggers mono, Q output of mono goes 
high and switches flip-flop, preparing mono to 
accept falling-edge trigger. Since 4047 locks out 
inputs until ft times out, mono triggers only on 
first falling edge occurring after its output goes 
low. Mono pulse length is about 2.5RC. With 60- 
Hz input clock, mono pulse length less than 8.33 
ms allows triggering on every transition, to give 
120-Hz output.— P. A. Lawless, One-Shot Forms 
Frequency Multiplier, EON Magazine, Aug. 5, 
1978, p 72. 







c1.C5.cs 

C2.C3 

c 4 



c 7 
c 8 

Ri 

R? 



1500'pF 

- 1000 pF 

- 8-35 pF 
-30pF 

- 2.3-20 pF 
1K« 

I0KJ! 



R3.R4 -220K!!. %W 



L 2 

RFC 

T1 



FET DOUBLER— Siliconix E300 matched FETs 
are connected as common-gate amplifiers in 
balanced push-push circuit giving up to 100% 
efficiency as frequency multiplier in UHF range. 
Series-tuned output trap LJC 6 increases rejec- 
tion of third-order harmonics to greater than 70 



- 4T #18 AWG. 5/16 DX 5/16 LG 
TAPPED 3/4T FROM COLD END 

- 2T #16 AWG 5/16 DX 3/16 LG 
1.2 uHy 

- RELCOM BT9 

5012 IN 4O0CT 400IJ OUT 

dB. Positive bias of 0.5 V is applied to FET gates 
to permit inclusion of balance control R 2 . Gain 
of doubler is about 1 dB. — "Analog Switches 
and Their Applications," Siliconix, Santa Clara, 
CA, 1976, p 7-52. 




SINE-WAVE DOUBLER— Frequency of sinusoi- 
dal input signal V s is doubled to give sine-wave 
output with total harmonic distortion less than 
0.6%. With input of 4 V P-P at 10 kHz, output is 
1 V P-P at 20 kHz. X and Y offset adjustments 
are nulled to minimize harmonic content of out- 
put. — "Phase-Locked Loop Data Book," Exar In- 
tegrated Systems, Sunnyvale, CA, 1978, p 9-16. 



404 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



K2& 



it- 

C, 0.5 uF 




OV„dc 



DOUBLER FOR TACHOMETER— Frequency of 
input from tachometer is doubled by charging 
and discharging of C, to reduce ripple in DC out- 
put voltage of tachometer circuit. Opamp 2 pro- 
vides bias current for opamp 1, while Q, drives 



large load currents and provides DC level shift 
required for bringing output voltage to zero 
when input frequency is zero. — T. Frederiksen, 
Frequency-Doubling Tach Operates from a Sin- 
gle Supply, EDN Magazine, June 5, 1977, p 208. 




73.333 MHz ON THIRD OVERTONE— Simple 
crystal oscillator circuit requires only one tripler 
for multiplying to 220-MHz amateur band. 
Mode suppression is provided by 10-itH coil 
which, with 4.5-pF capacitance of crystal holder, 
is series resonant at 24 MHz. — H. Olson, Fre- 
quency Synthesizer for 220 MHz, Ham Radio, 
Dec. 1974, p 8-14. 



1 r^h f 

ul J 01 \ \n 



1 



_n_n_ 



lHz-lXHz 
INPUT TO BE 
MEASURED 



100Hz - 10kHz 

VCO 

(1/240461 



+100 
145181 



WIDEBAND 

B DETECTOR 

11/2 4046) 



X10O OUTPUT TO 
FREQUENCY COUNTER 



LOOP FILTER 
100K 



i 2.2MF 
(TANT.I 



AF MULTIPLIER— Multiplies 1-100 Hz input sig- 
nal by 100 to permit measuring frequency with 
ordinary counter. Half of 4046 PLL is connected 
as 100-10,000 Hz VCO whose output is divided 
by 100 in 4518 dual divide-by-10 counter for 
comparison with input signal in other half of 
PLL connected as wideband phase detector. 
Output of detector goes to loop filter and to 
VCO for locking VCO at 100 times input fre- 
quency. — D. Lancaster, "CMOS Cookbook," 
Howard W. Sams, Indianapolis, IN, 1977, p 364- 
366. 




Jl 



JL 



J L_JL 

i- J i 



PULSE DOUBLER— Generates pulses at twice 
pulse input frequency. Input pulse at first mono- 
stable of 74123N makes it run for time T A . Neg- 
ative edge, terminating T A , triggers second 



monostable which runs for time T B . If T A equals 
half of input period and T B equals width of input 
pulse, desired result is achieved wherein addi- 
tional pulse is generated between input pulses. 






EXCLUSIVE-OR gate combines both pulses at 
output. Values shown for R and C will double 
frequency of 800-jus-wide input pulses having 
repetition rate of about 130 per second. — K. R. 
Brooks, Pulse Rate Doubler, Wireless World, 
April 1976, p 63. 



FREQUENCY MULTIPLIER CIRCUITS 



405 




-O OUTPUT 



100-200 MHz 

LI 12 turns no. 28 (0.3mm) on Amidon T25-12 toroid 

core 

L2 7 turns no. 24 (0.5mm), air core, closewound on 0.1" 

(2.5mm) diameter 



C3- 
L3 
C4- 
L4 
L2 




DOUBLING 100 MHz — Recommended for use vents damage if the polarity is reversed. — J. 
with VHF/UHF converters having inputs of 90 to Reisert, VHF/UHF Techniques, Ham Radio, 
120 MHz. Diode in series with power supply pre- March 1976, p 44-48. 



series resonant at approximately 5/7(110 

MHz), 1 fXH and 0.6-10 pF 

series resonant at approximately 3/7(110 

MHz), 2.2 jUH and 0.6-10 pF 

0.5 /Uh (parallel resonant at 110 MHz 

with 4.5-pF holder capacitance) 



110 MHz ON SEVENTH OVERTONE— Requires 
only one doubter for use in 220-MHz amateur 
band. Series-resonant traps are at frequencies 
of undesired lower modes. — H. Olson, Fre- 
quency Synthesizer for 220 MHz, Ham Radio, 
Dec. 1974, p 8-14. 



'i«0- 



'/.SN54L04 
_Ll \_23 




.4 5 



OUT J IN«2 



n r~i 



R A SN5486 




3_ 5 



-*/W* • Q+ 5 



k 



11 10 14 

SN54121 
3 4 7 



-Q 'out 



POINT A 



POINT C 



-TLTLTLTL. 



PARTS 

1 - SN54L04 

1 - 3N5486' 

1 - SN54121 
"R T - 2k to 30 k 
•C, - 10 pF to 10 uF 



DOUBLER FOR 1 Hz TO 12 MHz— Simple ar- quency doubling in digital systems, along with delay.— V. Rende, Frequency Doubler Operates 
rangement of EXCLUSIVE-OR, mono, and hex waveform symmetry. Article gives design equa- from 1 Hz to 12 MHz, EDN Magazine, Aug. 20, 
inverter ICs provides extremely accurate fre- tion. Series inverters create about 120 ns of 1976, p 85. 



CHAPTER 36 

Frequency Synthesizer Circuits 



Covers methods of generating up to 2500 different discrete frequencies in 
audio and RF spectrums, generally by setting thumbwheel switches or by 
keyboard control, for use in test equipment, receivers, and transceivers. 



VCO 41-50 MHz 




41-50, 50-60, AND 60-71 MHz— Three inde- ment provides two independent outputs at low 

pendent low-noise VCOs are used in 41 -7 1MHz thesizer. Outputs are chosen by selector switch. impedance.— U. L. Rohde, Modem Design of 

frequency synthesizer. Control voltage is ob- Texas Instruments SN72733 wideband ampli- Frequency Synthesizers, Ham Radio, July 1976, 

tained from phase-comparator output of syn- tier is used for decoupling. Cascade arrange- p 10-23. 



406 



FREQUENCY SYNTHESIZER CIRCUITS 



407 



1.1-1.6 MHz IN 10-Hz STEPS— Data input re- 
quirement is parallel BCD with 10-V CMOS lev- 
els and five digits. Reference input is 1-MHz sine 
or square with at least 1 V P-P. VCO covers 110- 
160 MHz in 1-kHz steps, operating in loop hav- 
ing 1-kHz reference. VCO signal is divided by 
100 to give final output in 10-Hz steps. L1 is 6 
turns No. 22 on 3- mm form, tapped at 2 turns. 
RFC is 6 turns No. 28 on F7 54- 1-06 ferrite bead. 
T1 is Mini-Circuits Lab T16-1 broadband RF 
transformer.— R. C. Petit, Frequency Synthe- 
sized Local-Oscillator System for the High-Fre- 
quency Amateur Bands, Ham Radio, Oct. 1978, 
p 60-65. 




n-VW-i 




BCD 
SWITCH 
lOOKHz 



BCD 
SWITCH 
lOKHz 



BCD 
SWITCH 




ALL PULLDOWN 

RESISTORS 

820k 



SWITCH 
lOOhz 



BCD 
SWITCH 

. 10Hz 



408 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+5V 



£2K 



SQUARE WAVE 
INPUT FROM VCO 
V 



f 




INTERSIL 
7038 



" • ' /h 



Ql =GENERAL PURPOSE 
NPN TRANSISTOR 



SQUARE WAVE OUTPUT 
TO PIN I OF MC4044 



REFERENCE OSCILLATOR 
8, 192,000Hz DIVIDED BY 
8!92 = 1,000Hz 

THIS INTEGRATED CIRCUIT HAS AN 
INTERNAL DIVIDE BY 8192 COUNTER 



FREQUENCY/PHASE LOW 
DETECTOR PASS 

FILTER 



VOLTAGE CONTROLLED OSCILLATOR 



1-9 kHz PLL — Simple experimental phase- audio range, for easy monitoring with head- setup procedure. — G. R.Allen, Synthesize Your- 
locked loop circuit synthesizes frequencies in phones. Article gives theory of operation and self!, 73 Magazine, Oct. 1977, p 182-188. 



(BIAS ADJUSTMENT) 
10K 



+5V 



SIGNAL INPUT 
60Hz 



»■ 6kHz 

OUT SQ. WAVE 
5V p-p 




PLL WITH COUNTER— Frequency multiplies 



tion is achieved with Signetics NE564 PLL by in- input frequency determined by counter; with square-wave output. — "Signetics Analog Data 
setting counter in loop between VCO and phase connections and values shown, multiplication Manual," Signetics, Sunnyvale, CA, 1977, p 
comparator. VCO is then running at multiple of factor for 60-Hz input signal is 100, giving 6-kHz 830-831. 



FREQUENCY SYNTHESIZER CIRCUITS 



409 




ATI 



TENS 



>TO MC4044, PIN 3 



THOUSANDS 



7.000-7.999 MHz PLL— Provides output in 1- low-pass filter at output of VCO to eliminate all are set to give desired division ratio. Article 

kHz steps under digital programming, except frequencies above 7.999 MHz, or use different gives theory of PLL synthesizers.— G. R. Allen, 

that first digit is hard-wired to 7 and does not VCO. 74123 mono lengthens reset pulse gen- Synthesize Yourself!, 73 Magazine, Oct. 1977, 

change. VCO is Motorola MC4024, which gen- erated by divide-by-N circuit. Terminals A, B, C, p 182-188. 

erates square-wave output. For sine output, use and D of 74192s go to grounding switches that 



CARRY 

OUT 

TO NEXT- 

HIGHER 

DECADE 



L 



CLOCK 



Q 

D 



BCD ADDER 



3 



Q 

D 



s, s 4 s 2 s, 

7483 STAGE 2 



b. b. b, b. 



r <P 



16 



Lhg=ltCJ^ 

^^-i— H 1/4 7408 



14 



*n _^^ j 



i5 



r 13 

C IN 1 

r-1 1 

io X 



s, s. 



Co 



BCD 
DATA INPUT 




7483 STAGE 1 
a, a. 



10 



13 



CARRY 
IN 
.FROM 
NEXT 
LOWER 
DECADE 



SWITCH-CONTROLLED ADDER— Direct BCD four D flip-flops whose outputs arefed back and be doubled and output of accumulator used to 

input from thumbwheel switch and use of stan- added to switch states. Frequency range de- clock flip-flop.— D. W. Coulbourn, Set Fre- 

dard crystal frequencies are primary advan- pends on number of decades used. Output quency Synthesizer with Thumbwheel 

tages of accumulator stage of synthesizer, one pulse may be used directly for synchronization. Switches, EON Magazine, April 5, 1975, p 115 

decade of which is shown. BCD adder drives If square wave is needed, clock frequency can and 117. 



410 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



221.86 MHz 
FROM VCO 




220-MHz PHASE-LOCKED— Fail-Child 95H90 di- 
vide-by-10 counter U3 is used to divide 221.86- 
MHz VCO output frequency by 10. Resulting 22- 
MHz output of U3 is compared in phase with 
output of 22-MHz crystal-controlled oscillator 
by phase comparator U1, which is standard 
double-balanced mixer. Output of phase detec- 
tor is passed through active low-pass filter for 
control of VCO. Article gives filter and VCO cir- 
cuits. U2 is 5-V voltage regulator for 95H90. — H. 
Olson, Frequency Synthesizer for 220 MHz, 
Ham Radio, Dec. 1974, p 8-14. 



HXX>\ 
TO LOW- PASS FILTER 



• DEC A>- 



♦ DEC A>- 



RFC 



• DEC A>— 



;p i siok v -- :! t — • 



T~M — I — 1 



-X 



50pF 
500pF 



30 pF 

-)r- 



- ■»""" r =fMVI04 x 
i X |IOOK = 

«m "^ 1 Z 



hk©- 



-f-^ | T ) \ " 5 

*' ?OnF I 



DECA>— If 



100 
TO 
UNUSED 
CRYSTAL SOCKET 




140-150 MHz IN 5-kHz STEPS — Developed for crystal oscillator. Digital edge-triggered Hughes operation of circuit in detail, and gives construe- 

use with amateur 2-meter radios, to give direct HCTR320 phase comparator maintains inputs of tion details as well as circuit for keyboard entry 

choice of frequency by setting thumbwheel or both frequency and phase coherence at lock; system. Power supply is 723 precision regulator 

lever switches. Phase-locked loop gives precise lock range is thus capture range, making lock- giving 7. 15 V. — M.I. Cohen, A Practical 2m Syn- 

high-purity output. Input frequency to system ing on harmonics impossible. Article describes thesizer, 73 Magazine, Sept. 1977, p 146-151. 
is 4.551 111 1-MHz reference signal from CD4060 



FREQUENCY SYNTHESIZER CIRCUITS 



411 











REMOVE 
REMOVE 


CI9. ADD JUMPER 
R24 a R25 




Ul 
4044 


UIO 
7400 












2 






















ADD JUMPER 
lOOKHi 


tOKHt 




1 

1 


MHz 








N 


nit 




111! 




till 






5* 


a 


U7 
8281 


8 12 


U8 
8280 


8 12 


U9 
B2B0 


« 














no 




9 


I— RE PL 
WITH 

11 7m0 


828 


UT 


9 


* 


2 

•+- FLIP -FLOP BITS PARTIAL SCHEMATIC 
— 4 AND 2 = 6 OF GLB 4008 

L T __ 

-6O0 KHz 
J \j OFFSET LOGIC 

7400 P~*i \l 








1 - 


~2~\ S 1 "* w H-Z[ \8 



600-kHz OFFSET— Developed for use with 
GLB400B frequency synthesizer which uses 
programmable divider and has outputs availa- 
ble from each flip-flop. Requires only two ICs, 
shown below horizontal dashed line. Select 
higher frequency of repeater pair on frequency- 
set switches. For operation at 146-147 MHz, se- 
lect offset T„ to transmit on repeater input. For 
147-148 MHz, select offset R x to receive on re- 
peater output. To operate in reverse, flip switch 
to other position. At center-off position, both 
transmit and receive are on selected frequency, 
with offset function disabled. LED lights only for 
offset.— D. Sargent, 600 kHz Offset for Fre- 
quency Synthesizers, Ham Radio, July 1978, p 
98. 




146.000-147.995 kHz SYNTHESIZER— De- 
signed for use with Drake TR-33C transceiver. 
Circuit has built-in offset providing choice of 
any 5-kHz-spaced channel in frequency range 



for transmit and receive frequencies. Only two 
crystals are required. Desired frequency can be 
entered with BCD thumbwheel switches. Tune- 
up and testing procedures are given. D1 is 



1N5530, D2 is 1N5144, and other diodes can be 
1 N914 or equivalent. Unmarked bipolar transis- 
tors are fast-switching silicon types; NPNs can 
be 2N2222, and PIMPs can be 2N4403— J. Moell, 
Super Deluxing the TR-33, 73 Magazine, April 
1978, p 72-74. 



412 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



*fOfc NOMINAL 
LOWER RESISTANCE 
GIVES MORE HYSTERESIS 



55-MHz PRESETTABLE COUNTER— High-speed 
four-decade counter with preload switches 
gives positive output pulse 30 ns long at 55 MHz 
to ensure that all counters are preset to right 
digit and transients have died out at end of 
count. If counters are preset to 5555, input fre- 
quency is counted until count gets to 9997. Next 
clock pulse triggers auxiliary flip-flop to initiate 
load pulse (2 cycles long) and get back to zero. 
Total count is 10,000 minus 5555, or 4445 (10- 
kHz output for 44.5-MHz input). Article covers 
construction and testing. Counter draws less * 
than 300 mA at 5 V. Developed for use in 2- 
meter frequency synthesizer. — H. Cross, High- 
Speed Divide-by-N Counters, Ham Radio, 
March 1976, p 36-38. 




A B C O PRELOADS 

\ V V V DATA {PRESET) INPUT THROUGH 
9 9 9 9 COMPLEMENT-OE-NINES-COMPLEMENT SWITCH 



nB II IIP 13 III 



I 



15 |9 \2 U2 

i 1 i i ►— 



fkl3\4 HO |3 win 



5 \9 \2 \I2 




ft'JH UP 13 1/) 



£ 



SN74I96 OR 97 



e*^ 




SN74SII2 OR SII3 



^ 






.MOW7W 
'OUTPUT 
(TO 
COUNTER) 



HAMLIN 3909 
4 1/2 DIGIT LCD 
REFLECTIVE 




KBD DETAIL 



R0W frequency. When key is depressed, mono (one- play decoder/driver. LED display may be used in 

shot) fires, causing CD4022 counter to incre- place of LCD display if current drain is not im- 

KEYBOARD ENTRY WITH 4VDIGIT DISPLAY — ment. At same time, keyswitch places appro- portent. Keyboard lockout switch prevents ac- 

Developed to give keyboard entry of desired f re- priate BCD data on input lines of 74C192 cidental change of frequency. — M. I. Cohen, A 

quency for 2-meter frequency synthesizer, as presettable decade counters. Output from Practical 2m Synthesizer, 73 Magazine, Sept. 

alternative to thumbwheel-switch setting of counters goes to synthesizer input and to dis- 1977, p 146-151. 



FREQUENCY SYNTHESIZER CIRCUITS 



413 



T 



5IK 5.1 K 



I" 



XR2240 SYNTHESIZER— Circuit uses XR2240 
programmable timer/counter for simultaneous 
multiplication of input frequency FR by factor of 
M and division of input frequency by factor of 
N + 1, where M and N are integers selected by 
appropriate connections of binary pins 1-8 to 
common output bus. Output frequency is then 
FR(M)/(1 + N) where M is between 1 and 10 in- 
clusive and N is between 1 and 255 inclusive. 
VCC is 4-15 V.— H. M. Berlin, IC Timer Review, 
73 Magazine, Jan. 1978, p 40-45. 




SINGLE-CONVERSION SYNTHESIZER— Used transmit and 455 kHz below channel frequency grammable divider.— L. Sample, A Linear CB 
in single-conversion CB transceiver in which during receive. 5.120 MHz is quintupled to Synthesizer, IEEE Transactions on Consumer 
VCO operates at channel frequency during 25.600 MHz to mix and provide input to pro- Electronics, Aug. 1977, p 200-206. 



414 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




_. R X OUT FIRST MIXER \ 

U 16.27 MHz TO 16.710 MHz T X O +J R X 



o 

TxOUT 10V 

26.965 MHz to 
27.405 MHz 



DUAL-CONVERSION SYNTHESIZER— Single- 
crystal transceiver system uses 10.240-MHz ref- 
erence frequency which is added to VCO fre- 
quency to produce transmit frequency. Same 
10.240-MHz reference frequency is mixed with 
first IF signal to generate 455-kHz second IF sig- 
nal. Dividing reference by 2 provides 5.120-MHz 
signal that is lightly coupled to multiply-by-3 
buffer whose output is tuned to third harmonic 
(15.360 MHz). This is mixed with VCO frequency 
to provide input signal for programmable di- 
vider. When VCO is operating as first mixer and 
local oscillator on CB channel 1 (16.270 MHz), 
difference frequency is 910 kHz. Programmable 
divider divides by 182 to give necessary 5-kHz 
input to phase detector. If VCO moves off fre- 
quency, divided input to phase detector moves 
away from 5 kHz and action of loop pulls VCO 
back on frequency. — L. Sample, A Linear CB 
Synthesizer, IEEE Transactions on Consumer 
Electronics, Aug. 1977, p 200-206. 



FREQUENCY SYNTHESIZER CIRCUITS 



415 



*o — Wv 




- RC 

, N •. 255 




255-FREQUENCY SYNTHESIZER— Circuit as 
shown for programmable counter section of 
Exar XR-2240 programmable timer/counter pro- 
vides square-wave outputs at 255 discrete fre- 
quencies from given internal time-base setting. 
Output is positive pulse train with pulse width 
T determined by values of B and C. Period is 
equal to (N + 1)T where N is programmed count 
in counter of IC. Counter output connections to 
output bus determine value of N; if pins 1, 3, and 
4 are connected to bus, Rl is 1 + 4 + 8 or 13 and 
period is 14T. Supply voltage range is 4-15 V. 
If counter cannot be triggered when using sup- 
ply above 7 V and less than 0.1 pf for C, connect 
300 pF from pin 14 to ground. — "Timer Data 
Book," Exar Integrated Systems, Sunnyvale, 
CA, 1978, p 11-18. 



1K Rl 



REFERENCE INPUT 




2500 FREQUENCIES WTTH SYNCHRONIZA- 
TION— EXAR XR-2240 programmable timer/ 
counter containing 8-bit programmable binary 
counter and stable time-base oscillator can gen- 
erate over 2500 discrete frequencies from single 
input reference frequency. Circuit simultane- 
ously multiplies input frequency by factor M 
and divides by N + 1, where M and N are ad- 
justable integer values. Output frequency F is 



equal to input frequency F R multiplied by M/(1 
+ N). M and N can be externally adjusted over 
broad range, with M between 1 and 10 and N 
between 1 and 255. Multiplication factor M is 
obtained by locking on harmonics of reference. 
Division factor N is determined by prepro- 
grammed count in binary counter section, es- 
tablished by wiring appropriate pins 1-8 to out- 
put bus. Input reference is 3 V P-P pulse train 



with pulse duration ranging from 30% to 80% 
of time-base period T. R, determines value of iyl. 
C is in range of 0.005 to 0.1 fiF, and R is between 
IK and 1 megohm for maximum output fre- 
quency of about 200 kHz. With M = 5 and N = 
2, 100-Hz clock synchronized to 60-Hz line fre- 
quency is obtained. — 'Timer Data Book," Exar 
Integrated Systems, Sunnyvale, CA, 1978, p 31- 
32. 



CHAPTER 37 

Function Generator Circuits 



Used for generating various combinations of sine, square, and triangle 
waveforms, usually with manual or external variations of frequency in AF or 
RF ranges by DC control voltage. Also includes circuits for generating cubic, 
quadratic, hyperbolic, trigonometric, ramp, and other mathematical 
waveforms, as well as circuits for converting one of these waveforms to one 
or more others. See also Multivibrator, Oscillator, Pulse Generator, Signal 
Generator, and Sweep chapters. 



FSK SINE-SQUARE-TRIANGLE GENERATOR— 
Exar XR-2206 modulator-demodulator 
(modem) is connected as function generator 
providing high-purity sinusoidal output along 
with triangle and square outputs, for FSK ap- 
plications. Circuit has excellent frequency sta- 
bility along with TTL and CMOS compatibility. 
Total harmonic distortion in 3 V P-P sine output 
is about 2.5% untrimmed, but can be trimmed 
to 0.5%. High-level data input signal selects fre- 
quency of 1/R 6 C 3 Hz, while low-level input se- 
lects 1/R 7 C 3 Hz. For optimum stability, R„ and R, 
should be in range of 1 0K to 100K. Adjust R 8 and 
R g for minimum distortion. — "Phase-Locked 
Loop Data Book," Exar Integrated Systems, 
Sunnyvale, CA, 1978, p 57-61. 



SINE OR TRIANGLE 
FSK OUTPUT o 

Ofb 

+ 12V0- 




THD ADJ. 



SQUAREWAVE 
FSK OUTPUT 



4.7K 



"X" DIVISOR 
DIGITAL INPUTS 




^ 



GROUND 
PLANE 



R l. R2- R 3 " 10/ " METAL FILM 
ALL CAPS = CERAMIC DISC 



HYPERBOLIC A/X FUNCTION— Uses Precision 
Monolithics DAC-20EX D/A converter with OP- 
17G opamp to generate extended-range hyper- 
bolic functions of the type A/X, where A is an- 
alog constant and X represents decimally 
expressed digital divisor. R5 provides 
simultaneous adjustment of scale factor and 
output amplifier offset voltage. Same circuit 
serves for -A/X function if DAC reference am- 
plifier and output opamp terminals are re- 
versed. — W. Ritmanich, B. Blair, and B. 
Debowey, "Digrtal-to-Analog Converter 
Generates Hyperbolic Functions," Precision 
Monolithics, Santa Clara, CA, 1977, AN-23, p 2. 



416 



FUNCTION GENERATOR CIRCUITS 



417 



Vref 




BASIC SQUARE-TRIANGLE— Requires only two 
sections of LM324 quad differential-input 
opamp to provide choice of triangle or square- 
wave outputs at frequency determined by val- 
ues of components. Supply voltage range is 3- 
32 V. — "Quad Low Power Operational Ampli- 
fiers," Motorola, Phoenix, AZ, 1978, DS 9339 R1. 



WAVEFORM GENERATOR— Two Optical Elec- 
tronics 9008 integrators and 9813 comparator 
together generate choice of sine, square, and 
triangle waveforms suitable for system testing 
and display generation. Square wave is typi- 
cally ±13.5 V with 20-/XS transition time. Trian- 
gle wave is ± 10 V with betterthan 0.1% triangle 
linearity. Comparator senses zero crossings of 
sine-wave output to produce square waves, 
thus completing feedback loop. Integrators are 
commanded at pin 8 for zero output, so triangle 
and sine outputs can be made to start from 
zero. — "Waveform Generator," Optical Elec- 
tronics, Tucson, AZ, Application Tip 10257. 



GATE 



+10V TO OPERATE 
OV TO STOP 





0.01 Hz TO 100 kHz— Variable DC offset permits 
adjustment of average value of sine, square, or 
triangle waveform to any arbitrary plus or 
minus value within voltage swing capability of 
opamp U 3 . Buffer stage U 2 is inside feedback 
loop. Simple emitter-follower differentiator 
provides positive-going 1-V 0.5-/us output at 
sink terminal. Square-wave output is buffered 
by emitter-follower Cv — H. Olson, The Function 
Generator, CO, July 1975, p 26-28 and 71-72. 



418 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




TWO-PHASE VOLTAGE-CONTROLLED— Pro- 
duces fixed-amplitude sawtooth outputs that 
can be shaped to give sine waves, with outputs 
of the two identical channels differing by a spec- 
ified phase such as 90°. Each output is inte- 
grated to give rising or falling ramp that con- 
trols switching FET of opposite channel. With 
oscillation established, one integrator output 
goes toward zero and the other away from zero, 
with same or opposite polarity. When first out- 
put crosses zero, discriminator switches FET in 
input amplifier of other channel, with action 
being self-perpetuating to give desired saw- 
tooth outputs. Dashed-line gating at outputs of 
discriminators can be used to boost slope of one 
sawtooth in one quadrant. — F. B. Jones, Volt- 
age-Controlled Two-Phase Sawtooth Oscilla- 
tor, Wireless World, June 1973. p 285. 



zero-crossing triggers 

reversal on other 

waveform 



.1 



J~L 



iveform 
at'X' 




-AA-V— i 

R31 J_ 



1 Hz TO 2 MHz — Triang le wave is generated by 
switching current-source transistors to charge 
and discharge 1 timing capacitor. Precision dual 
comparator sets peak-to-peak amplitude. Sine 
converter requires close amplitude control to 



give low-distortion output from triangle input. 
Square-wave output is obtained at emitter of 
Q5, for driving current switches Q1-Q4 and 
LM318 output amplifier. Scaling permits ad- 
justing all three waveforms to ±10 V. Wave- 



forms are symmetrical up to 1 MHz, and output 
is usable to about 2 MHz.— R. C. Dobkin, "Wide 
Range Function Generator," National Semicon- 
ductor, Santa Clara, CA, 1974, AN-115. 



FUNCTION GENERATOR CIRCUITS 



419 



SINE-WAVE SHAPER— Uses CA3140 opamp as 
voltage follower, acting with diodes from 
CA3019 array to convert triangle output of func- 
tion generator or other source to sine wave hav- 
ing total harmonic distortion typically less than 
2%. — "Circuit Ideas for RCA Linear ICs," RCA 
Solid State Division, Somerville, NJ, 1977, p 5. 




TO WIDEBAND 

OUTPUT 

AMPLIFIER 



lOkrt 

EXTERNAL 
OUTPUT 



SWEEP 

WAVEFORM 

OUTPUT (l&V.pp) 



n_TL 

SQUAR6WAV6 
OUTPUT 
I3V. pp I 




= COUPLING CAP 
= BYPASS CAP 



VOLTAGE-TUNED WITH 10:1 FREQUENCY 
RANGE— Exar XR-S200 PLL IC is connected to 
generate basic periodic square or sawtooth 
waveform. Multiplier section, used as linear dif- 
ferential amplifier, converts differential saw- 
tooth input waveform to triangle wave. 5K pot 
connected between pins 8 and 9 rounds peaks 
of triangle to give low-distortion sine wave with 
less than 2% total harmonic distortion. Output 
frequency can be swept or frequency-modu- 
lated by applying proper analog control input. 
For linear frequency modulation with less than 
10% deviation, modulation is applied between 
pins 23 and 24. For larger deviations, negative- 
going sweep voltage V s is applied to pin 18 as 
shown. Digital control input pins 15 and 16 can 
be used for FSK applications; if this is not de- 
sired, pins are disabled by connecting to ground 
through current-limiting resistor. — "Phase- 
Locked Loop Data Book," Exar Integrated Sys- 
tems, Sunnyvale, CA, 1978, p 9-16. 



SINE/COSINE— Uses National SK0003 sine/co- 
sine look-up table kit consisting of four MOS 
ROMs and three output adders. Combination 
implements equation sin = sin M cos L + cos 
M sin L. Worst-case error is 1 5/8 bits in least 
significant bit. Cosine is approximated with loss 
in resolution of 1 A bit in 11-bit input or 'A bit in 
10-bit input. — "Memory Databook," National 
Semiconductor, Santa Clara, CA, 1977, p 6-98— 
6-99. 



EX OR GATES GATES 

DM74B5s OM88121 









J 


NEXT ^ 




MSB O ' 


, ) 








, ) 







)D-0 



JD-O 



3: 



)CK> 



I • 



ISB O- 



30-£> 



SINE/ 
COSINE i 
SIGNAL 



"0" - Sine 
"1" = Cosine 



SK0003 

ROUS 

ANO 

OUTPUT 

ADDERS 



• 2 s 

, 2'° 
■ 2" 



420 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



R1>1 meg 



CI* 



*SEE TEXT 




wv\ 



-tail- 



SQUARE-TRIANGLE AF— Two sections of 
LM3900 quad opamp are connected to generate 
dual-polarity triangle- and square-wave AF out- 
puts while operating from single supply, by 
using current mirror circuit at noninverting 
input. Value used for CI determines frequency 
and pulse width; frequency ranges from 0.5 Hz 
with 1 /*F to 3800 Hz with 0.0001 pF and 21 kHz 
with C1 omitted. Pulse-width range is 35 /is 
without C1 to 1 .6 s with 1 /*F.— F. M. Mims, "In- 
tegrated Circuit Projects, Vol. 5," Radio Shack, 
Fort Worth, TX, 1977, 2nd Ed., p 57-63. 



R16jl00fi 




AF SINE-SQUARE-TRIANGLE— Can be tuned wave. IC3 acts as integrator converting square- 
over entire audio spectrum in four ranges for wave output of IC1 to triangle wave. IC4-IC6 
generation of low-distortion waves for labora- form state-variable filter for removing sine- 
tory use. IC1 converts sine wave to square wavecomponentfromtrianglewave. IC2issim- 



ple inverting amplifier for output. — R. Melen 
and H. Garland, "Understanding IC Operational 
Amplifiers," Howard W. Sams, Indianapolis, IN, 
2nd Ed., 1978, p 130-134. 



FUNCTION GENERATOR CIRCUITS 



421 




R9 
200K 



- HK*h 



20-20,000 Hz SINE-SQUARE— Opamp is used 
as tuned circuit driven by square wave from 
voltage comparator. Frequency is controlled by 
R1-R3, CI, and C2, with R3 providing tuning. 
Comparator is fed with resulting sine wave to 
obtain square wave for feedback to input of 
tuned circuit, to cause oscillation. Zener stabi- 
lizes amplitude of square wave that is fed back. 



t C1 =C2 

i Frequency Adjust 

* Amplitude Adjust 

F„. 1= 

2-C, % R 3 R, 

R6 and C5 provide DC negative feedback around 
comparator to ensure starting. Values of CI and 
C2 are equal, and range from 0.4 juF for 18-80 
Hz to 0.002 iiF for 4.4-20 kHz.— "Easily Tuned 
Sine Wave Oscillators," National Semiconduc- 
tor, Santa Clara, CA, 1971, LB-16. 




0.5-25 kHz TRIANGLE— Diode bridge and FET 
form constant-current source charging C„ to 
make voltage across C, change at linear rate as 
required for triangle output across C,. Fre- 
quency can be adjusted from 500 Hz to above 
20 kHz with constant output amplitude, by 
means of R,. Short-term stability is better than 
1 part in 10,000. Since the same R and C are used 
to generate both sections of the waveform, pos- 
itive and negative slopes are identical. Diodes 
are HP 5082-2810.— G. R. Begault, Op Amp 
Makes Variable-Frequency Triangular Wave 
Generator, EDN Magazine, Sept. 15, 1972, p 42- 
43. 




100k (1%) 
RO— t-WV*— 



RESOLVER— Circuit accepts DC input voltages systems to convert rectangular to polar coor- is obtained by shifting first output 90° in phase. 

R and X and generates two DC output voltages dinates. Sine wave is generated by chopping Circuit also generates proper sampling pulses 

R sin X and R cos X. Can be used in guidance input signal R and filtering resulting square and contains two sample-and-hold circuits on 

computers to solve coordinate conversion wave. Sine wave is then sampled at time con- outputs.— W. H. Licata, Solid-State Resolver, 

problems (polar to rectangular) and in feedback trolled by X to generate R sin X. Cosine output EDN Magazine, July 20, 1 973, p 82-83. 



422 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




100-Hz SQUARE-TRIANGLE— Two-opamp os- 
cillator delivers ±13 V square waves and ±10 V 
triangle waves simultaneously at 100 Hz for val- 
ues shown. By scaling R„ R 2 , and C, wide range 
of frequencies can be covered down to 0.1 Hz 
(increase R 2 to 10 megohmsforfrequencies near 
lower limit). Square-wave rise time is about 1.5 
ps and fall time 0.5 /us. Opamp A, operates as 
integrator and A 2 as Schmitt trigger. — R. S. Bur- 
wen, Triangular and Square Wave Generator 
Has Wide Range, EDN Magazine, Dec. 1, 1972, 
p59. 



oJUUl 




FSK 
OUTI 



FSK SQUARE-TRIANGLE GENERATOR— Uses 
Exar XR-2207 FSK modulator connected for sin- 



ENABLE/DISABLE OR 
CHANNEL SELECT 



gle-supply operation, to produce triangle or 
square FSK outputs for either single-channel or 
two-channel multiplex operation. Used in trans- 
mitting digital data over telecommunication 
links. Table gives equations for selecting timing 
resistors Rj-R^ resistor values are in ohms, C 



Logic Level 


Active Timing Resistor 


Output Frequency 


Pin 8 


Pin 9 


L 


L 


Pin 6 


1 

CqRj 


L 


H 


Pins 6 and 7 


1 + ' 
C R, C R 2 


H 


L 


Pin 5 


1 


C R 3 


H 


H 


Pins 4 and 5 


1 , 1 


C R 3 C R 4 



is in farads, and frequency is in hertz. For opti- 
mum stability, R, and R 3 should be in range of 
10K to 100K. For two-channel multiplex, make 
connections shown by dotted lines. — "Phase- 
Locked Loop Data Book," Exar Integrated Sys- 
tems, Sunnyvale, CA, 1978, p 57-61. 



+ 15V 



10k 



100k 




*-0V 



-15V 



0.1-, 1-, 10-, 100-, and 1,000-Hz SINE-SQUARE- 
TRIANGLE — Provides choice of five spot fre- 
quencies switched in decades by S,. Setting of 
S 2 determines shape of output waveform. Ad- 
just R„ R 3 , and R 5 to make peak-to-peak ampli- 



tudes of all three waveforms equal. R 4 controls 
symmetry. R 2 is adjusted for minimum distor- 
tion of sine-wave output. Output may be set up 
to 100 mA by R 6 , and is short-circuit-proof. DC 
level may be set anywhere between ±14 V by 



-15V 

R 7 . Motorola 1438 IC and 741 opamp boost out- 
put of 8038 IC sufficiently to drive most labo- 
ratory loads. — G. R. Wilson, Low-Frequency 
Generator, Wireless World. Feb. 1977, p 44. 



FUNCTION GENERATOR CIRCUITS 



423 



# matched 



2N363B 




1000:1 FREQUENCY SWEEP— Permits varying 
output frequency of function generator over 
wide frequency range by using pot to vary con- 
trol voltage V c . Network consisting of two tran- 
sistors and two diodes replaces usual charging 
resistor of Miller integrator in function genera- 
tor, and has output current varying exponen- 
tially with input voltage. Electronic switch 
using pair of transistors is controlled by Schmitt 
trigger of function generator, which connects 
+V C and — V c alternately to charging circuit. If 
frequency pot is mechanically connected to 
strip-chart recorder. Bode plots of audio equip- 
ment can be made over entire audio range. — P. 
D. Hiscocks, Function Generator Mod. for Wide 
Sweep Range, Wireless World, Aug. 1973, p 
374. 



w jit 



CURRENT-CONTROLLED SQUARE-TRIANGLE 
GENERATOR — CA3080 opamp is connected as 
current-controlled integrator of both polarities 
for use in current-controlled triangle oscillator. 
Frequency depends on values of C and opamp 
bias current and can be anywhere in audio 
range of 20 Hz to 20 kHz. Square-wave output 
is obtained by using LM301A opamp as Schmitt 
trigger.— S. Franco, Current-Controlled Trian- 
gular/Square-Wave Generator, EDN Magazine, 
Sept. 5, 1973, p 91. 




VOLTAGE - CONTROLLE D 

CURRENT SOURCE Q+7SV 




_TL 



SINGLE CONTROL FOR 1,000,000:1 FRE- 
QUENCY RANGE— Uses two RCA CA3130 
opamps and CA3080A operational transcon- 
ductance amplifier to generate square and tri- 



angle outputs that can be swept over range of 
0.1 Hz to 100 kHz with single 100K pot R1. Al- 
ternate voltage-control input is available for re- 
mote adjustment of sweep frequency. IC1 is op- 
erated as voltage-controlled current source 
whose output current is applied directly to in- 



tegrating capacitor C1 in feedback loop of in- 
tegrator IC2. R2 adjusts symmetry of triangle 
output. IC3 is used as controlled switch to set 
excursion limits of triangle output when square 
wave is desired. — "Linear Integrated Circuits 
and MOS/FET's," RCA Solid State Division, So- 
merville, NJ, 1977, p 236-244. 



424 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



^ 100k 

O — v/v- 




CONTENTS 



VOLTAGE-CONTROLLED NONLINEAR— Circuit 
produces function E = X Y ' 2 , where X is input 
voltage in range of +10 mV to +10 V and Y is 
analog programming voltage in range of -0.4 

V to -10 V. Uses Optical Electronics 2534 tem- 
perature-compensated log feedback elements, 
+5 V reference, two high-frequency opamps, 
and one low-frequency opamp. 2534 produces 
log conversion of input signal. 5898 multiplier 
serves to vary scale factor of log signal. With 
offsets used as shown, + 10 V input will always 
produce +10 V output regardless of Y input. To 
set up, adjust R4 until output does not change 
with Y for +10 V input, then adjust R7 for +10 

V output with +10 V input. — "Voltage-Con- 
trolled Non-Linear Function Generator," Optical 
Electronics, Tucson, AZ, Application Tip 10263. 



0.5 Hz TO 1 MHz SINE-SQUARE-TRIANGLE— 
Uses Exar XR-2206 IC function generator in sim- 
ple circuit that operates from dual supply rang- 
ing from ±6 V to ± 12 V. Withl-pF capacitor for 
C, 2-megohm frequency control covers range of 
0.5-1000 Hz. Range is 5-10,000 Hz with 0.1 pF, 
50 Hz to 100 kHz with 0.01 /iF, and 500 Hz to 1 
MHz with 0.001 j*F. Designed for experiments 
with active filters. — H. M. Berlin, "Design of Ac- 
tive Filters, with Experiments," Howard W. 
Sams, Indianapolis, IN, 1977, p 9-10. 



220&. 



\ : 



JUMPER 
OPEN 



I 

u - . 



EXTERNAL . 

TIMING ;*; C 
CAPACITOR T Q 



r< 



I kft 

FRED [ 

I ■< 2 M& 



V -V 

.01 



+ V 



(?Jj2$J 



XR 
2 2 06 



47kft 



I IOk& 
I WV — o 



DC OFFSET 



O t\, OR \ 

OUTPUTS 



SQUARE WAVE 
PULL-UP(TO+V> 



O+V 
33kXl I 



-J- .1 iiF 

LX 



ioo kA 

OUTPUT 
LEVEL 



-V 



TLT 



J7T 



SQUARE-WAVE 
INPUT 



S 
D Q 



C Q 
R 



D Q 
IC, B 

c 



R, 
-Wv» •- 

390k 



C,1 
13 0.1 fiF 



10 



PHASE DETECTOR 



AMPLIFIER AND PHASE ADJUST \ 



R. 47k 



y " | >nnr- 

R 2> I2l^? v « 

f R 3 ic^E-^. 



100k 3 



IC, = CD4013 DUAL TYPED FLIP FLOP 

IC 2 = 741 OP AMP 

IC 3 = 8038 WAVEFORM GENERATOR/VCO 



R 5 
20k 



R 6 

Ik 



R 7 

300k I 




ZLI 



FILTER 



C SINE-WAVE OUTPUT 



SQUARE TO SINE WITH PLL— 8038 waveform 
generator simultaneously generates synthe- 
sized sine wave and square wave. Square-wave 
output closes phase-locked loop through 741 
opamp IC? and dual flip-flop IC,, while sine-wave 
output functions as converted output. Center 



frequency is 0.15/R 9 C 3 . R 10 should be at least 10 
times smaller than R 9 . If center frequency is 400 
Hz, capture range is half that or ± 100 Hz. When 
input is applied, phase comparator generates 
voltage related to frequency and phase differ- 
ence of input and free-running signals. IC2 am- 



plifies and offsets phase-difference signal. Sine 
output has less than 1% distortion, DC com- 
ponent of 0.5 V cc , and minimum amplitude of 
0.2 V cc P-P — L. S. Kasevich, PLL Converts 
Square Wave into Sine Wave, EDN Magazine, 
June 20, 1978, p 128. 



FUNCTION GENERATOR CIRCUITS 



425 



ci 



Vpos 
o 



.02 MF 
C2 

If— 

.002uF 



1MQ ' 




R7 >10K 



R4 



i m 



Vpos 

p 



€) 



R2 > 100K 



100 MF 



-OAC 

OUTPUT 



-ODC 



Vpos 




Q2 



R5 ^100K 



<D 



Rll 




VARIABLE SQUARE-TRIANGLE— Dual pot R1- 
R3 varies frequency over range of 15-500 Hz 
when CI is in circuit and 150-4800 Hz when C2 
is in circuit. Each output has amplitude control. 
Opamps are Motorola MC3401P or National 
LM3900, and transistors are 2N2924 or equiva- 
lent NPN. Supply can be 12 VDC— C. D. Rakes, 
"Integrated Circuit Projects," Howard W. Sams, 
Indianapolis, IN, 1975, p 19-20. 



-o Vneg 



input at 16 times 
output frequency 



PHASE REVERSING 
CONTROL INPUT 



*EXACT VALUES OF CAPACITORS DEPEND UPON THE DESIGN 
FREOUENCY. REMOVE CAPACITORS ENTIRELY TO SEE UN- 
FILTERED STAIR STEP FUNCTION 




C4 (MINI-DIP) 



i ^ — , SINE 

♦-VW— f— C_] WAVE 
1 OUT 



POWER CONNECTIONS - 

+5V GNO 
ICI 7486 14 7 
IC2 7486 14 7 
IC3 7493 5 10 



DIGITAL FOURIER— Sine-wave generator pro- 
duces Walsh-function approximation of sine 
function. Frequency of sine wave is set by 
square-wave input to pin 14 of 7493. Filter com- 
ponents of opamp help smooth staircase wave- 
form generated by summing Walsh-function 
components as weighted by resistors. Circuit is 



converter consisting of digital expander that 
expands input square wave into variety of dig- 
ital waveforms and analog combiner that adds 
these waveforms to produce periodic analog 
output. Negative signs of Walsh harmonics are 
handled with digital inverter, and magnitudes 
are handled by choice of resistor value in sum- 



ming junction. Signs and magnitudes are under 
microprocessor control. Net output is stairstep 
approximation to desired output, which can be 
smoothed by low-pass filter. — B. F. Jacoby, 
Walsh Functions: A Digital Fourier Series, 
BYTE, Sept. 1977, p 190-198. 



426 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 12V 
O 




TRIANGLE-TO-SINE CONVERTER— Nonlinear 
emitter-base junction characteristic of 511B 
transistor array is used for shaping triangle out- 
put of 566 function generator to give sine out- 
put having less than 2% distortion. Amplitude 
of triangle is critical and must be carefully ad- 
justed for minimum distortion of sine wave by 
varying values of R,, R 2 , and input level pot 
while monitoring output with Hewlett-Packard 
333A distortion analyzer. — "Signetics Analog 
Data Manual," Signetics, Sunnyvale, CA, 1977, 
p 851-853. 



PULSE/SAWTOOTH GENERATOR— Pulse out- 
put is obtained from Exar XR-2006C function- 
generator IC when pin 9 is shorted to square- 
wave output at pin 11. Pulse duty cycle, along 
with rise and fall times of ramp from pin 2, is 
determined by values of R1 and R2. Both can be 
adjusted from 1 to 99% by proper selection of 
resistor values as given in formulas alongside 
diagram. — E. Noll, VHF/UHF Single-Frequency 
Conversion, Ham Radio, April 1975, p 62-67. 




9 T 
a — » 



XR - 2006C 



PULSE 
OUTPUT 
O 



'I 



SAWTOOTH 
OUTPUT 
O 



I • |- [I/IRI < 02)] 

DUTY CYCLE' RI/(Rt*R2) 



ZO pF 




SINGLE FREQUENCY CONTROL— Adjustment 
range of over 1,000,000 to 1 for frequency is 
achieved by using CA3080A as programmable 
current source, CA3160 opamp as voltage fol- 



lower, and CA3080 variable opamp as high- 
speed capacitor. Variable capacitors C1-C3 
shape triangle waveform between 500 kHz and 
1 MHz. C4 and C5 with 50K trimmer in series 



with C5 maintain constant amplitude within 
10% up to 1 MHz. — "Circuit Ideas for RCA Linear 
ICs," RCA Solid State Division, Somerville, NJ, 
1977, p 6. 



FUNCTION GENERATOR CIRCUITS 



427 




REDUCING DISTORTION— Use of UAF41 uni- 
versal active filter at output of function gener- 
ator reduces distortion of sine-wave output by 
eliminating some of harmonics. In typical ap- 
plication, two-pole active filter reduces 1% dis- 
tortion down to 0.1%, using low-pass configu- 
ration. Article gives design equations. For 1-kHz 
cutoff, R, should be 159.2K — Y. J. Wong, De- 
sign a Low Cost, Low-Distortion, Precision Sine- 
Wave Oscillator, EDN Magazine, Sept. 20, 1978, 
p 107-113. 



1 MHz — Simple sinusoidal generator using Exar 
XR-2206C IC provides sine, triangle, or square 
outputs. For sine output, SI is closed and R A and 
R B are adjusted for minimum distortion. Exact 
output frequency f is 1/RC where R is about 2 
megohms from pin 7 to ground and C is con- 
nected between pins 5 and 6. FM output is ob- 
tained when modulating input is applied to 
either pin 7 or 8. For AM output, modulation is 
applied to pin 1.— E. Noll, VHF/UHF Single-Fre- 
quency Conversion, Ham Radio, April 1975, p 
62-67. 



SOUARE WAVE 
OUTPUT 




SINE/TRIANGLE 
OUTPUT 



-10V 




NONUNEAR CUBIC AND QUADRATIC— Pro- 
vides four-quadrant operation with high accu- 
racy over input amplitude range of several 
decades. Applications include analog com- 
putations for radar and ballistic problems. 



linearization of transducer characteristics, and 
teaching theory of quadratic equations. Article 
gives design equations and complete design 



procedure. — H. McPherson, Non-Linear Func- 
tion Generator, Wireless World, Oct. 1972, p 
485-487. 



428 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




innnr 



NEGATIVE RAMP— Connection shown for 566 
function generator gives negative output ramp 
having period equal to 1/2f where f is normal 
free-running frequency of 566 as determined by 
supply voltage and RC values used. Ramp has 
very fast reset because PNP transistor charges 
timing capacitor C, rapidly at end of discharge 
period. Short output pulse is available at pin 
3. — "Signetics Analog Data Manual," Signetics, 
Sunnyvale, CA, 1977, p 851. 



5>I,2,3,4-R ( ( -p*£- 



(WAVEFORM GENERATOR) 
Rl IOK 



THREE-WAVEFORM— Gives simultaneous 

sine, square, and triangle outputs with low dis- 
tortion (1%), high linearity (0.1%), 0.05 Hz to 1 
MHz frequency range, and duty cycle of 2% to 
98%. Intersil 8038 waveform generator feeds 
buffer amplifier using 2N3709 transistor, 
switched to desired output waveform. Timing 
capacitors C1-C8, determining frequency de- 
cades of signal generator, start with 500 juF for 
0.05 Hz to 0.5 Hz and decrease in submultiples 
of 10 to 500 pF for 50 kHz to 500 kHz. C8 is 250 
pF for final range of 100 kHz to 1 MHz— H. P. 
Fisher, Precision Waveform Generator, 73 Mag- 
azine, Dec. 1973, p 41-43. 




(EQUALIZER ATTEN.) 



(BUFFER AMPLIFIER) 



-o — vw- 



vv o — vw- 




-O SIGNAL OUT 



1 — 1 


1 — 1 
-o 


1 — 1 


1 — 1 

I 1 


1 — \ 


1 — 1 
o— 


1 — 



CI-C8 (SEE TEXT) 



AMPLITUDE 
ADJUST 




ru 



100S! SINE 
]% WAVE 

OUTPUT 



6 6 



12V 6 



3R1C, 

FET TRIANGLE TO SINE CONVERTER— Use of 
nonlinear transfer characteristic of P-channel 
junction FET to shape triangle output of 566 



function generator gives sine wave having less 
than 2% distortion. Amplitude of triangle wave 
is critical and must be carefully adjusted for 



minimum distortion of sine output. — "Signet- 
ics Analog Data Manual," Signetics, Sunnyvale, 
CA, 1977, p 851-852. 



FUNCTION GENERATOR CIRCUITS 



429 



,7*<3 



BREAK 
HERE AN 
ADD DIODE V 

TIMING 7 "* • 
RESISTOR 



C 



ADD DIODE 
ANY SMALL 
SIGNAL 
GERMANIUM 
TYPE 



INTERSIL 
8038 



10 



TIMING 
CAPICITOR • 



S10k 



4— O 



-O 10-15V 
@10mA 



SQUARE WAVE 



81k 



*"*! 



OUT 



_ft TRIANGLE WAVE 
~OUT 

■OSINE WAVE 
OUT 



DIODE CANCELS SUPPLY CHANGES— Adding 
any small-signal germanium diode to Intersil 
8038 sine-square-triangle function generator as 
shown will compensate for changes in supply 
voltage. When using diode, change from 10 to 
IS V produces only 5-Hz change in output over 
frequency range of 100-10,000 Hz. Technique 
can be applied to other IC function generators, 
such as Signetics 565, as well as to 555 timers. — 
R. Liebman, Single Diode Compensates IC Os- 
cillator, EDN Magazine, April 20, 1974, p 87. 




-oE„ 



, >ioksi K 



R,?10l(!l 



20-20,000 Hz SQUARE TRIANGLE— R, and C, 
are chosen for upper frequency limit of 20 kHz, 
and oscillator is adjustable down to lower limit 
of 20 Hz with R 5 . Circuit will operate up to 100 



1_TLT 



-OE 




kHz if component values are suitably changed. 
A 2 should be offset-nulled by adjusting for best 
symmetry at lowest frequency. Total width of 
T of output waveform varies between 50 /is and 



50 ms at frequency range covered. — W. G. Jung, 
"IC Op-Amp Cookbook," Howard W. Sams, In- 
dianapolis, IN, 1974, p 381-383. 



,o4>>° 13^>^ 9 

V rr =14 Gnd = 7 



out 

2k2 



"X 



+V rr 9V 




DRIVEN CONSTANT-AMPLITUDE SAW- 
TOOTH — Gives constant-amplitude output 
over input frequency range of 2-100 kHz. Input 
signal from SN74121 IC is 300-ns pulse that 
drives basic sawtooth generator Tr,-Tr 2 . Result- 



ing sawtooth waveform is amplified by opamp 
A, of MC3401P four-opamp package and fed to 
A 2 which acts as comparator for amplitude-sen- 
sing. 25K threshold-setting pot is adjusted for 
maximum linearity of amplitude versus fre- 



quency. Rectangular-wave output of A 2 is fil- 
tered to give control voltage that is shifted in 
level by A 3 and D, to meet input voltage require- 
ments of Tr 2 . Desired sawtooth output appears 
at source of Tr 3 . — J. N. Paine, Constant Ampli- 
tude Sawtooth Generator, Wireless World, Oct. 
1975, p 473. 



430 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



Dl D2 




AAA 



TRIANGLE-WAVE CLIPPER— Triangle-wave 
generator using 566 function generator is con- 
nected to RS741C opamp for clipping positive 
and negative peaks of triangle waves. Output as 
seen on CRO is modified square wave with slop- 
ing side. Clipping level depends on voltage rat- 
ings of zeners used. Supply voltages can range 
from 1 .5 to 9 V each. Can be used for classroom 
demonstrations. — F. M. Mims, "Integrated Cir- 
cuit Projects, Vol. 4," Radio Shack, Fort Worth, 
TX, 1977, 2nd Ed., p 37-44. 



CLIPPED OUTPUT 



TRIANGLE TO SINE — Expression approximat- 
ing sine function from to 90° is generated by 
function fitting and duplicated by using AD534L 
analog multiplier and appropriate close-toler- 
ance (0.1%) resistors. Accuracy of sine wave is 
within ±0.5% at all points. Linearly increasing 
voltage of triangle develops rising sinusoidal 
output. Conversely, linearly decreasing input 
generates mirror of rising sinusoids. Increasing 
triangle waveform, then bringing it back to zero 
again, completes full cycle of sine-wave out- 
put. — R. Frantz, Analog Multipliers — New IC 
Versions Manipulate Real-World Phenomena 
with Ease, EDN Magazine, Sept. 5, 1977, p 125- 
129. 



+1SVO 0-i 




.Q TRIANGULAR 
WAVE 
INPUT 




30-20,000 Hz SQUARE-TRIANGLE— Uses 555 
timer as bilevel threshold detector, together 
with A, as bidirectional constant-current source 
and A 2 as buffer amplifier. If buffered triangle 
output is not needed, opamp A 2 can be omitted. 



A, charges C t between +5 and + 10 V threshold 
points of 555 to give linear triangle output for 
buffering by A 2 . Simultaneously, toggling of 555 
between its high and low output generates 
square wave of about 13 V at pin 3, along with 



TTL 
SQUARE 
WAVE 



5-V TTL output at pin 7 for additional square- 
wave output and for controlling state of A,. — 
W. G. Jung, Build a Function Generator with a 
555 Timer, EDN Magazine, Oct. 5, 1976, p 110. 



FUNCTION GENERATOR CIRCUITS 



431 




OVpos 



».36R|C| 
t = 1 kHz AS SHOWN 



1 kHz SQUARE-TRIANGLE— National LM386 
opamp operating from 9-V supply generates 1- 
kHz square wave at 0.5 W for driving 8-ohm 
loudspeaker or other load. Exact frequency is 
determined by values used for R, and C,. Tri- 
angle output can be taken from pin 2. Pins 1 and 
8 can be shorted because DC offset voltages are 
unimportant. — "Audio Handbook," National 
Semiconductor, Santa Clara, CA, 1977, p 4-30- 
4-33. 



R1A 




-oVneg 



90-900 Hz SINE-SQUARE-TRIANGLE— Ganged 
10K dual pot covers range when C is 0.25 /iF for 
8038CC waveform generator. Other values of C 
(from 0.005 pF to 2.2 fiF) give different fre- 
quency ranges between 10 Hz and 50 kHz. Lin- 
earity of waveforms depends on tracking pre- 
cision of dual pot. — C. D. Rakes, "Integrated 
Circuit Projects," Howard W. Sams, Indianapo- 
lis, IN, 1975, p 116-120. 



E.O— 



£)' 



\W — • — >**- 



MULTI FUNCTION 



CONVERTER ^ff [ 1^ 

», •, a847R ' ZL > 

e - 3 -sm, SM r XTX35C 



FOR 0<e,/E R <2 

HYPERBOLIC SINE— Burr-Brown 4302 multi- 
function converter and opamp generate hyper- 
bolic sine transfer function with response 
matching ideal curve within 0.7%. Technique 
permits setting powers and roots at fractional 
as well as integer values. Converter shown is 
set for exponent of 3.2. Choice of amplifier gain 
and reference voltage scales response for given 
input and output signal levels. Article gives de- 
sign equations. — J. Graeme, Sinh Generator 
Boasts 0.7% Error, END Magazine, Aug. 5, 1978, 
p 70 and 72. 



+15V 

o 



I 



v+ 



A 
555 



OUT 



GND 



C 4 
0.01 /*F 







-% 



1-kHz SINE-SQUARE— 555 timer starts as 
astable MVBR but then acts with A 2 to form 
multiple-feedback bandpass filter that removes 
harmonics from square wave to give sine-wave 
output with distortion less than 2%. Sine out- 
put is fed back to timer through C, which now 
operates as Schmftt trigger, shaping sine wave 
to give output square wave. Frequency is de- 
termined primarily by filter components C,, C2, 
R„ and R 2 . Output is about 9 V P-P.— W. G. Jung, 
"IC Timer Cookbook," Howard W. Sams, Indi- 
anapolis, IN, 1977, p 203-204. 



SQUARE-TRIANGLE VCO— Wfth DC control 
voltage of 5 mV to 5 V, circuit controls fre- 
quency of both square and triangle outputs 
with good linearity. Peak value of triangle out- 
put is precisely set at 2.44 V and V by reference 
voltages at noninverting inputs of comparators. 
Comparator A2 drives load for low outputs, 
while comparator A1 drives load when output 
is high. Article tells how circuit works. — R. C. 
Dobkin, Comparators Can Do More Than Just 
Compare, EDN Magazine, Nov. 1,1972, p 34-37. 



SQUARE WAVE 
OUTPUT 




432 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




18-20,000 Hz SINE-SQUARE— Circuit uses two 
opamps to obtain necessary positive feedback 
for sustaining oscillation. RC network of first 
stage acts as tuned circuit, permitting operation 
only at frequency determined by values of R and 
C. Pot R3 provides tuning over significant fre- 
quency range. Pot R8 controls amplitude of sine 
output. Zener X1 stabilizes amplitude of square 
output. Sine signal is applied to LM111 acting 
as limhter to provide desired square wave. Table 
gives values of C1 and C2 for five different fre- 
quency ranges. — E. M. Noll, "Linear IC Princi- 
ples, Experiments, and Projects," Howard W. 
Sams, Indianapolis, IN, 1974, p 123-124. 



150 PF 



10 meg 



C1.C2 


MIN 
FREQ 


MAX 
FREQ 


0.47 |iF 


18 Hz 


80 Hz 


0.1 UF 


80 Hz 


380 Hz 


,022|iF 


380 Hz 


1.7 kHz 


.004?uF 


1.7 kHz 


8 kHz 


.002UF 


4.4 kHz 


20 kHz 



POSITIVE RAMP— NPN transistor across timing 
capacitor C, of 566 function generator gives fast 
charging of capacitor at end of discharge period, 
for positive ramp having very fast reset. Period 
of ramp is equal to 1/2f where f is normal free- 
running frequency of 566 as determined by sup- 
ply voltage and RC values used. — "Signetics 
Analog Data Manual," Signetics, Sunnyvale, 
CA, 1977, p 851. 




JUL 



"YVYV" '°9 



9 to 15V 



rr^V 





SINE-SQUARE-TRIANGLE WITH LIN/LOG 
SWEEP — Four-transistor circuit provides 
choice of linear or logarithmic sweeps for Inter- 
sil 8038 IC function generator. In linear mode, 
constant-current generator Tr 3 charges C, al- 
most linearly, with Tr,-Tr 2 resetting C, when its 



voltage reaches about one-third V cc plus 0.9 V. 
In logarithmic mode, positive feedback pro- 
vides exponential charging of C,. Voltage at B 
must be set experimentally because it depends 
on Vc,.. For overall frequency control, make R 5 



variable. Point A has short positive pulse that 
can be used to reset capacitor C of IC, and to 
sync an oscilloscope. — S. Villone, Linear/Loga- 
rithmic Sweep Generator, Wireless World, Dec. 
1976, p 42. 



FUNCTION GENERATOR CIRCUITS 



433 



[square WAVE* 
|GENERATOR 
R 2 



TRIANGULAR WAVE 
GENERATOR 



I- 




J . ^. 

OUTPUT LEVEL I ! v 

— w. wft v^ OSo 

1K +10K 25K 




AIN • OUTPUT AMPLIFIER 



2.5 Hz TO 250 kHz SQUARE-TRIANGLE— Five 
switched frequency ranges each give continu- 
ous variation of frequency over one decade and 
adjustment of output amplitude from 0.2 to 20 
V P-P. Slope of triangle is highly linear, and rise 
time of square wave is less than 1 00 ns. Square- 
wave generator is simple hysteresis circuit trig- 
gered by triangle generator. Output voltage is 
clamped to desired level by diodes connected 
to bandwidth control point. Output opamp is 
selected for high slew rate. S 3 gives choice of 1 
or 10 for gain. Maximum output current should 
be limited to 20 mA. — "Linear & Data Acquisi- 
tion Products," Harris Semiconductor, Mel- 
bourne, FL, Vol. 1, 1977, p 7-25 (Application 
Note 510). 



1 Hz TO 100 kHz SQUARE-TRIANGLE— Wide- 
range function generator built around LM111 
comparator provides two different output 
waveforms whose frequency can be varied over 
five decades by R„ from 1 Hz to 100 kHz. Two 
transistor pairs are used to vary charging cur- 
rent of timing capacitor exponentially. Output 
current from transistor pairs is controlled by lin- 
ear pot so rotation of pot is proportional to log 
of output frequency. Sensistor R 2 provides tem- 
perature compensation for transistor pairs. — R. 
C. Dobkin, Comparators Can Do More Than Just 
Compare, EDN Magazine, Nov. 1, 1972, p 34-37. 



15V~ 

20 mA 

O 



1A 



f5-6V 
O 



1,000(1 



14. 
CD4011AE 
7 



vh 




22Ck 
SYMMETRY 



Otriangular wave 3V 
O square wave 5V 



SINE-SQUARE-TRIANGLE AT 3-5 V — Uses to sine-wave converter. Sine-wave approxima- sawtooth and pulse waveforms at desired fre- 



CD401 1 1C operating from 1 5-V AC line as at left. 
NAND gates of IC are connected as at right, with 
G, serving as integrator with variable delay 
time, G 2 -G 3 as Schmitt trigger, and G 4 as triangle 



tion, depending on transfer function of G<, is cal- 
ibrated by R 3 and R 4 . Values of R, and R 2 may be 
varied between 0.01 and 10 megohms and C 
between 100 pF and 2.2 pF to obtain desired 



quency determined by setting of R 5 . — J. W. 
Richter, Single I.C. Function Generator, Wire- 
less World, Nov. 1976, p 61. 



434 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




O +5V 



SQUARE WAVE 
OUTPUT 



HIGH-PRECISION TRIANGLE— Opamp circuit 
provides easily controlled peak-to-peak ampli- 
tude of triangle wave suitable for use in sweep 
circuits and test equipment. Positive and neg- 
ative peak amplitudes are controllable to accu- 
racy of about ±0.01 V by DC input. Output fre- 
quency is likewise easily adjusted over range of 
two decades. Circuit consists of integrator and 
two comparators. One comparator sets positive 
peak, and other sets negative peak. Operating 
frequency depends on R1, C1, and reference 
voltages. Maximum difference in reference volt- 
ages is 5 V. Frequency limit is about 200 kHz. — 
R. C. Dobkin, "Precise Tri-Wave Generation," 
National Semiconductor, Santa Clara, CA, 1973, 
LB-23. 



+ 15 V 




CENTERING 

100 
-I5V kfl 



100 kfl 

FROM BUFFER 

METER DRIVER > f 



Wr 



(0PTI0NAL) 



, . FREQUENCY 

39kfl! l2 0a >0 i a ADJUSTMENT 



;5 * 

>kO 



•15 V 



+ 15 V 



' A/ 



TO 
SINE 
WAVE 
SHAPER 



THIS NETWORK IS USED WHEN THE 
OPTIONAL BUFFER CIRCUIT IS NOT 
USED 



OUTPUT 
AMPLIFIER 




HIGH 

FREOUENCY 
LEVEL 
7-60 pF 

-* 



I kfl 
10 kU 

EXTERNAL 
OUTPUT 



REMOTE FREQUENCY CONTROL— Frequency 
of square and triangle outputs can be adjusted 
over range of 1,000,000:1 with 10K pot or by 
varying DC voltage applied to pin 5 of CA3080A 
over wire line from remote location. CA3140 



serves as noninverting readout amplifier for tri- 
angle wave developed across integrating ca- 
pacitor network at output of CA3080A current 
source. Second CA3080 acts as high-hysteresis 
switch having trip level established by four 



diodes, to give desired square-wave output. — 
"Linear Integrated Circuits and MOS/FET's," 
RCA Solid State Division, Somerville, NJ, 1977, 
p 248-254. 



CHAPTER 38 

Game Circuits 



Included are chip connections, VHF modulators, score generators, and sound 
effects for variety of TV games, along with electronic dice, roulette wheel, 
coin tosser, robot toy, model railroad switch, six-note chimes, and attention- 
getting LED displays. 



RIFLE — Developed for use with General Instru- 
ments AY-3-8500-1 TV game chip to simulate 
target practice with rifle. Player aims at bright 
target spot moving randomly across TV screen. 
If gun is on target when trigger is pulled, pho- 
totransistor in barrel picks up light from target 
and generates pulse for producing sound effect 
of hit and incrementing player's score. PT-1 can 
be TIL64 or equivalent phototransistor. 4098 is 
dual mono, and 4011 is quad two-input NAND 
gate. Pulse outputs go to pins of game chip. 
Article gives all circuits but covers construction 
only in general terms. — S. Ciarcia, Hey, Look 
What My Daddy Built!, 73 Magazine, Oct. 1976, 
p 104-108. 





+9 V to pin 14 of 401 1 and 4001, and pin 16 of 4050. 
Return to pin 7 of 4011 and 4001, and pin 8 of 4050. 

SIX-TONE CHIME— Separate AF oscillators, 
gated on by six-stage time-delay circuit, gen- 
erate six different chime tones. Loudspeakers 



can be mounted so each tone comes from dif- 
ferent location in house. When doorbell button 
is pushed, each tone generator is turned on in 



sequence for period determined by individual 
time controls. System operates from 9-V bat- 
tery, with CMOS logic drawing very little 
standby current. — J. Sandler, 9 Projects under 
$9, Modern Electronics, Sept. 1978, p 35-39. 



435 



436 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




*6 2V 



DIGITAL NOISEMAKER— Simple sound-effect 
generator for video games, electronic cash reg- 
isters, and electronic toys uses one-fourth of 
LM3900 quad opamp chip as 2-kHz signal gen- 
erator that can be turned on or off by input con- 
trol voltage. Suitable for applications that do 
not require pure sine wave. Output transistor 



Qi, needed with low-impedance voice coil, is 
not critical as to type. For smaller acoustic out- 
put, Q, can be replaced by 100-ohm resistor if 
1 00-ohm voice coil is used, to avoid overloading 
IC. — T. Frederiksen, Build a Transformerless 
Tone Annunciator, EDN Magazine, April 5, 1977, 
p 141-142. 





r -Zj N 68*1 



IOnF k T J* 




a B 

I j, 1 y 
MAIN LED^i ij (A) SIDI 



T 



+ 5 TO IC'S 
NG LED 



~T 



-s 



2N2222 




2MH 



2-MHz MASTER CLOCK— Developed for use 
with General Instruments AY-3-8500-1 TV game 
chip, which contains dividers that deliver re- 
quired 60-Hz vertical and 15.75-kHz horizontal 
sync signals for video signal going to TV set. 
Coil is Miller 9055 miniature slug-tuned. Article 
gives other circuits for game. — S. Ciarcia, Hey, 
Look What My Daddy Built!, 73 Magazine, Oct. 
1976, p 104-108. 



-^ *N 




WHO'S FIRST?— One of LEDs comes on to in- 
dicate which of two people pushes button first 
after event such as stopping of music. Circuit 
requires two 7400 quad gates. — Circuits, 73 
Magazine, Nov. 1974, p 142. 



DD » C1D , 0°] GROUND 

jT] TO SWITCH COIL-MAIN 

TO SWITCH COIL-SIDING 

B 

B 

B 

B 
B 



} 



SEPARATE + 12V SUPPLY 1 
AMP, (UNREGULATED) 
USED FOR SWITCHES 

CONTROL-SHORT TO GROUND TO THROW SWITCH TO 
MAIN LINE 

CONTROL-SHORT TO GROUND TO THROW SWITCH TO 
SIDING 

LED TO +5 TO INDICATE SWITCH IN MAIN (THIS POINT 
LOW) 

LED TO +5 TO INDICATE SWITCH IN SIDING 

+5 VOLTS IN FOR ICs 

POINTS 4 AND 5 CAN BE PARALLEL TO MANUAL 
MOMENTARY SWITCHES AND LOGIC SWITCHES-ANY 
PULSE (LOW) WILL WORK, HOLDING POWER ON ABOUT J4 
SECOND, 74121 WITH RESISTOR AND CAP CONTROL 
TIME. 



MODEL RAILROAD SWITCHING— Control cir- 
cuit is used to drive solenoid-operated track 
switches of typical HO train layout. Input can be 
pair of complementary TTL signals from 8008 or 
other computer or can be from manual switch 
SI. 74121 mono MVBR controls time that 




8 OHM tin 
SPEAKER 



switch is energized in given direction. Output 
transistors are rated at 20 W, enough for driving 
solenoids taking 1 A at 12 V. Use protective 
diodes across coils of solenoids. — H. De Mon- 
stoy. Model Railroad Switch Control Circuit, 
BYTE, Oct. 1975, p 87. 



9V SCR^ — ^ REED SWITCH 



^ 



~7h 



SMALL MAGNET GLUED TO REED ( ^ — 

SWITCH MAKES IT NORMALLY CLOSED 

HOWLING BOX— Tone oscillator driving loud- 
speaker is sealed into wood or plastic box, with 
reed switch mounted on one face of box and 
pushbutton of other switch projecting out 
through hole in box. Place "DO NOT TOUCH" 
label on button. When button is pushed despite 
warning, SCR latches and applies power to AF 
oscillator. Only way to turn off howling is to 
hold large permanent magnet against location 
of reed switch, to oppose field of magnet glued 
on switch and make reed contacts open. If mer- 
cury switch is used in box in place of pushbut- 
ton, alarm goes off when box is picked up. — P. 
Walton, Now What Have I Done?, 73 Magazine, 
May 1975, p 81. 



GAME CIRCUITS 



437 




TV GAME CONTROLLER— Single General In- 
struments 8500 IC contains most of electronics 
needed for pong, hockey, squash, or practice 
games using screen of TV set. Desired game is 
selected by grounding one of pins 20-23. Con- 
nect ball, player, and score outputs to four-input 
OR circuit to generate composite video for com- 
bining with sync output. Final output can be fed 
directly to video amplifier of TV set or fed to 
suitable RF modulator. Sound output is fed to 
loudspeaker through transistor audio amplifier. 
No connection on pin 5 gives two rebound an- 
gles, while grounding gives four rebound an- 
gles. Open pin 7 gives fast speed, and ground- 
ing gives slow speed. Open pin 13 gives small 
bats, and grounding gives large bats. — D. Lan- 
caster, "CMOS Cookbook," Howard W. Sams, 
Indianapolis, IN, 1977, p 166. 



♦o 
5-1SVdc 



^r- 



(see text) ( 



\ 



60-LED HYPNOTIC SPIRAL— LEDs are mounted 
on display board in spiral arrangement and 
wired in matrix connected to ICs so each LED is 




IC3 

I 4069 

. I *£lMS2 lh 



.01mF 



IC1 
4017 



m^iiii^ 



yy yyyyy y y y 



XX 



X 



x 



^c\-xxxxxxx^ 



xxxxxy.xxx^ 



xxxxxxxxy 



X 



X 



X 



£ 



Wx 



01-06 
1N914 



LE01-LED60 



lighted in sequence as IC1 and IC2 carry out 
counting function. IC3 is square-wave oscillator 
with frequency determined by C1 and setting of 
R2. Output pulses are used to clock IC1 to ad- 
vance count, with carry output of IC1 clocking 



IC2 every tenth count. At end of 60 counts, both 
ICs reset to zero for new sequence. Inherent cur- 
rent limiting of ICs makes dropping resistors 
unnecessary for LEDs. — F. Blechman, Digi- 
trance. Modem Electronics, Dec. 1978, p 29-31. 



438 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




RF OUTPUT 
TO ANTENNA 
TERMINALS 



VHF MODULATOR— Developed as interface be- 
tween General Instruments AY-3-8500-1 TV 
game chip and antenna terminal of TV set. Ad- 
just CI to frequency of unused channel to which 
receiver is set for playing games. Article gives 
all circuits but covers construction only in gen- 
eral terms.— S. Ciarcia, Hey, Look What My 
Daddy Built!, 73 Magazine, Oct. 1976, p 104- 
108. 



+5V> 



OSCILLATOR FOR CHANNELS 2-6— Transmit- 
ter serving as interface between video game 
and TV set can be tuned with L, to vacant chan- 
nel in low TV band. Regular antenna should be 
disconnected when output of oscillator is fed to 
TV set via twin-line, to avoid broadcasting 
game signals. L, is 4 turns No. 18 spaced 3/8 inch 
on 1 A-inch slug-tuned form. — B. Matteson, 
"King Pong" Game Offers Hockey and Tennis 
Alternatives to TV Re-Runs, BDN Magazine, 
Aug. 5, 1975, p 47-55. 




300S1 TWIN 

• LEAD TO TV 

ANTENNA 



+VCC 



CI 

ItVF 

15V 



RIFLE 
CIRCUIT 



R2 
lOOfl 



\D—\ 8fl 



SPEAKER 




2N2222 9CyH 



^1 



Ql 
2N2222 



T, -I-C2 



HI -T- 
I5K 
♦Aw • — 



S2 
GAMES SELECT 



11 



.C5 
-75pF 



.C6 
•75pF 



i 



RI5 
IK 



IC 4 
AY-3-8500-1 





V 



;C4 
• ImF 



1 




IC3 1/2 4072 
! CMOS 



R9 

330A 
-AVV 




SIX-GAME VIDEO— General Instruments AY-3- 
8500-1 MOS chip gives choice of hockey, 
squash, tennis, two types of rifle shoot, and 
practice games, all with sound effects and au- 
tomatic scoring on 0-15 display at top of TV 



screen. Can be used with standard TV receiver 
(using RF modulator circuit) or with video mon- 
itor. S4 grounds base of Ql when in manual- 
serve mode, to eliminate steady boing when 
ball leaves playing field. R5-R8 position players 



TO MODULATOR 

OR VIDEO TERMINAL 



on field. Article covers operation in detail and 
gives suitable rifle circuit. Supply is +6 V. 2-MHz 
clock is at upper right. — A. Dorman, Six Games 
on a Chip, Kilobaud, Jan. 1977, p 130, 132, 134, 
136, and 138. 



GAME CIRCUITS 



439 



MICROCOMPUTER OUTPUT PORT 



>2.2K 

; :i/2w 



d 



K POT 
(VOLUME CONTROL) 



220 

I/2W 

~-wt 



^SECONDARY SIDE 
(40) 



PRIMARY SIDE 
(500ft) 



PLOP FOR GAMES— Section 1 of 7406 TTL hex 
inverter can be attached to output port and dri- 
ven by program loop, to provide sound effects 
for computer games. When output port goes to 
logic 1 (greater than +2 V), action of inverter is 
such that paralleled inverters 3 and 4 go to and 
draw current through primary of T1, making 
loudspeaker produce single plopping sound. 
When output port goes to 0, another plop is pro- 
duced. If output port is switched between and 
1 fast enough, loudspeaker output will be tone 
at switching frequency. — D. Parks, Adding 
"Plop" to Your System, Kilobaud, May 1977, p 



HEADSrtAILS FLIPPER— Uses only half of 7400 
quad NAND gate as gated clock driving half of 
7473 JK flip-flop. With power switch closed, 
LEOs representing heads and tails flash on and 
off at clock frequency. Closing FLIP switch stops 
clock randomly, leaving one LED on to give 
equivalent of tossing coin for heads/tails call. — 
G. Young, JK Flip-Flops and Clocked Logic, Kilo- 
baud, July 1977, p 66-70 and 72-73. 



SILICON 
OFF. DIODE 

-5T^ W— 



:dpy_MJE)^ 



I.5V 1.5V 15V 15V 

-^'h — > — ^ — ^h- 



S~ 



CLK 

7473 



-# 



-#- 



— U.UI 





Model CTI55B Surface Acoustic Wave Output Modulation Filter. 

(Crystal Technology Inc., 2510 Old Middlefield Way, Mountain View, Calif . 94043). 



LONG THROW ,S! 3 V 
DPOT SLIDE / V-. Q 



ANT. 
INPUT 



SWITCH ■ir 

HOCKEY/TENNIS/HANDBALL— Uses National have sound. Circuit generates all necessary tim- interface directly to antenna terminals of set.— 

MM57100 TV game chip to provide logic for ing (sync, blanking, and burst) to interface with "MOS/LSI Databook," National Semiconductor, 

generating backgrounds, paddles, ball, and dig- circuit of standard TV receiver. With addition of Santa Clara, CA, 1977, p 4-37-4-47. 
ftal scoring. All three games are in color and chroma, audio, and RF modulator, circuit will 



440 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




OUTPUT TO DICE OK 
THER GAME CIRCUIT 



juuuiJiJiJTjn_n_r-L_p_n- 



DICE OR ROULETTE RUNDOWN— 4046 PLL 
connected as VCO is set at twice desired max- 
imum rate for dice or roulette-wheel counters. 
Pressing spin button momentarily to start ac- 
tion charges 1-jmF capacitor to supply voltage 
and jumps VCO to highest frequency. Output 
frequency then decreases rapidly as capacitor 
is discharged by 10-megohm resistor. Output is 
stopped by using retriggerable mono to drive 
other half of 4013 dual D flip-flop. When fre- 
quency drops below value at which mono times 
out, mono resets flip-flop and holds it to stop 
display. — D. Lancaster, "CMOS Cookbook," 
Howard W. Sams, Indianpolis, IN, 1977, p 252- 
254. 



jui_n_i — L 

FINAL OUTPUT 



3.S7955MHI 9-35 pf 



X^4K 




CUUMA»SYNC 



^ 



/"^1-EC 



J R4 

: 2 ;>k 



VIDEO MODULATOR— National LM1889N 
serves to interface audio, color difference, and 
luminance signals to antenna terminals of TV 
receiver. Circuit allows video information from 
video games, test equipment, videotape re- 
corders, and similar sources to be displayed on 
black-and-white or color TV receivers. LM1889N 



Oisv DC 



HF OUTPUT 

consists of sound subcarrier oscillator, chroma 
subcarrier oscillator, quadrature chroma mod- 
ulators, and RF oscillators and modulators for 
two low VHF channels. — "MOS/LSI Databook," 
National Semiconductor, Santa Clara, CA, 1977, 
p 4-48-4-49. 



S2 

SPST 
,. TOGGLE 

ED2 
L209 



/^"\LEl 




COIN FLIPPER— One of LEDs comes on when SI 
is pressed, to simulate tossing of coin. LEDs can 
be labeled HEADS and TAILS if desired. Transis- 
tor types are not critical. For true random re- 
sults, voltage between collectors of transistors 
should be V with S2 closed and SI open. — 
Circuits, 73 Magazine, June 1975, p 161. 



GAME CIRCUITS 



441 





CK)^>' 



2K 
-VA- 



X 



SCORE DISPLAY— National 5841 IC is used for 
display of video game scores on TV receiver, as 
well as for time and channel number displays. 
Properly conditioned H and V pulses must be 
applied to pins 18 and 19to interface TV. Output 
video on pin 15 must be buffered and summed 
into existing video inside TV set. Display posi- 
tion is controlled by H and V pots. Horizontal 
display size depends on clock frequency. 
Grounding M input gives only channel number. 
Positive voltage at M gives both channel and 
time. Grounding D input provides 5-slot time 
display, while positive D input gives 8-slot time 
display. Channel inputs are applied continu- 
ously in negative-logic form, with time inputs 
multiplexed externally. — D. Lancaster, "CMOS 
Cookbook," Howard W. Sams, Indianapolis, IN, 
1977, p 158. 



MODEL-TRAIN SWITCHING— Individual SCRs 
are triggered by logic-level signals indepen- 
dently to initiate discharge of large capacitor CI 
through solenoid of model railroad track 
switch. — D. W. Zimmerli, Two Hobbies: Model 
Railroading and Computing, Kilobaud, Aug. 
1978, p 62-68. 




CHARGER 




RLAh 



~t 1 — > h*~ 

"I+ 25v 

VU>6ET103 



RLBh 



RLCh 




100 lin 



* Taplin 4-5V geared motor 



AC- 



BO- 




^ 



\?V OCP71 




-OB 



DUAL-MOTOR ROBOT— Battery-operated toy 
car roams around room, reversing whenever it 
hits wall or obstacle, and returns automatically 
to home base when batteries are in need of 
charge. Small geared motor, such as Meccano 
No. 11057 or 4.5-V Taplin, is used for each rear 
wheel so reversal of one motor provides steer- 
ing. Single free-swivel ing caster is at front of 



machine. With head-on collision, both contacts 
of bumper close to reverse both motors so ma- 
chine backs away, turns, and proceeds in new 
direction. With glancing collision, motor on op- 
posite side is reversed so machine sheers away. 
White tape on floor, leading to charger having 
female jacks, is sensed by two phototransistors 
used to control motors so machine follows tape 



until probes at opposite end from bumper enter 
jacks. Circuit permits search mode for recharg- 
ing only when relay D senses low battery volt- 
age and energizes lamps that illuminate white 
tape. Article gives operation and construction 
details. — M. F. Huber, Free Roving Machine, 
Wireless World, Dec. 1972. p 593-594. 



442 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



■# 



e^ ir&- 




19 VO.T SUPPLY 



DICE SIMULATOR— Two 4018B synchronous 
counters are connected in modulo-6 walking- 
ring sequences for driving LEDs to produce fa- 
miliar die patterns. Pressing roll button starts 
gated astable that cycles first die hundreds of 
times and second die dozens of times, for ran- 
domizing of result. When roll button is released, 
final state of each die is held. — D. Lancaster, 
"CMOS Cookbook," Howard W. Sams, Indian- 
apolis, IN, 1977, p 324-325. 



RANDOM-FLASHING NEONS— Neon glow 
lamps such as Radio Shack 272-1101 flash in 
unpredictable sequences at various rates that 
are determined by values of R and C used for 
each lamp, to give attention-getting display for 
classrooms and Science Fairs. Value of R1 can 
be as low as 2200 ohms for higher repetition 
rates, but battery drain increases. When circuit 
is energized, each neon receives full voltage and 
fires. Lamp capacitor begins charging, decreas- 
ing voltage across lamp until lamp goes out and 
cycle starts over. Use of different capacitor val- 
ues makes lamps recycle at different rates. T1 
is 6.3- VAC filament transformer used to step up 
oscillator voltage. — F. M. Mims, "Transistor 
Projects, Vol. 2," Radio Shack, Fort Worth, TX, 
1974, p 43-52. 



R -1-10 MEGOHM 

C ■ .01-1 ||F, 2C0 VOLTS 





DICE — Simple low-cost arrangement of three 
ICs operating from 5-V battery (four nickel-cad- 
mium or alkaline cells) provides bar display cor- 
responding to spots on six sides of die. Uses 



SN7490N TTL decade counter with SN7405 hex 
inverter to drive Minftron 3015F seven-segment 
display. Article describes operation in detail and 



suggests variations for Arabic and binary dis- 
plays. — G. J. Naaijer, Electronic Dice, Wireless 
World, Aug. 1973, p 401-403. 



GAME CIRCUITS 



443 



LEFT 
PLAYER 



2 MEG <{. INPUT > 



)GAME SELECT (CLOSE ONE 
SWITCH ONLY) 




VIDEO OUT 



tice circuit. All operate from battery supply at 
SIX-GAME CHIP — General Instruments AY-3- MHz master clock whose output is divided in lower left. Article covers construction only in 
8500-1 TV game chip and associated circuits chip to get vertical and horizontal sync frequen- general terms. — S. Ciarcia, Hey, Look What My 
give choice of six different games. Article gives cies, VHF modulator used between game and Daddy Built I, 73 Magazine, Oct. 1976, p 104- 
addftional circuits required, including that for 2- antenna terminal of TV set, and rifle target prac- 108. 





PIN 


NO. 




V DO 


GND 


IC, 


14 


7 


IC 7 


14 


7 


IC, 


16 


8 


IC, 


16 


8 



TOUCH 

plate r~7 




sik r , 
\P Tooi„ 





8 




, 9 


IC »« 


11 




° 2 f 





N.C. 



IC,' CD4011 ORMC14011 (QUA0 2-INPUTNAND) 

ICj= CD4013OR MC14013 (DUAL "D" FLIP FLOP) "± 

IC,- CD4510OR MC14510 (BCD UP/DOWN COUNTERl 

IC 4 = CD4511 OR MC14511 (LATCH/DECODER/DRIVER) 

LED.- HP5082-7740 (SEVEN SEGMENT INDICATOR) COMMON CATHODE 



LED DIE — When positive bias on input of IC 1D 
NAND gate is pulled to ground by skin resis- 
tance of finger, D flip-flop ICu connected as 
mono is triggered. Pin 1 goes high for about 2 
s, making IC 4 latch outputs of counter IC 3 and 
unblank LED display. Random time that finger 
is on touch plate determines randomness of 



number displayed. Number can be between 1 
and 9, between 1 and 6 for die, or between 1 and 
2 to represent heads or tails. Change BCD value 
of jam inputs of IC 3 to highest random number 
desired. Values shown are for 4.5-V supply and 
display current of 10 mA per segment. LED is 



blanked until plate is touched. Standby current 
drain of 10 pA on three AA alkaline cells is so 
low that ON/OFF switch is unnecessary. — C. 
Cullings, Electronic Die Uses Touchplate and 7- 
Segment LED Display, EDN Magazine, May 20, 
1975, p 70 and 72. 



CHAPTER 39 

IF Amplifier Circuits 



Gives circuits for most common IF values used in single-conversion and 
double-conversion superheterodyne receivers, including noise blanker, CW 
filter, Q multiplier, and T attenuator variations. See also Frequency 
Modulation, Receiver, Single-Sideband, Television, and Transceiver chapters. 




TO AGO AMP 



455-kHz WITH PRODUCT DETECTOR AND 
BFO — Used in 1.8-2 MHz communication re- 
ceiver having wide dynamic range. Input comes 
from diode-switched bandpass filter giving 
choice of 400-Hz or2.1-kHz bandwidths. Output 
for AGC amplifier is taken from primary of T3. 
AGC voltage, ranging from +2 V for minimum 



gain to +9 V for maximum gain, is applied to 
pins 7 of both IF opamps. Product detector uses 
quad 1N914A diodes. Varicap CR10 and R1 vary 
BFO output from 453 to 457 kHz. Two-part ar- 
ticle gives all other circuits of receiver. — D. 
DeMaw, His Eminence — the Receiver, QST, 
Part 2— July 1976, p 14-17 (Part 1— June 1976, 
p 27-30). 



POLY. ■ POLYSTYRENE 



00,000-ohm linear-taper 

composition control (panel mount). 
RFC11 - 2.5-mH miniature choke (J. W. 

Miller 70F253A1). 
RFC12 - 10-mH miniature choke (J. W. 

Miller 70F102A1). 
CR6-CR9, incl. — High-speed silicon, 

1N914A or equiv. 
CR10 - Motorola MV-104 Varicap 

tuning diode. 
L16 - Nominal 640-mH slug-tuned 

inductor (J. W. Miller 9057). 
L17 — Nominal 60-mH slug-tuned 

inductor (J. W. Miller 9054). 
T2, T3 - 455-kHz i-f transformer. See 

text. (J. W. Miller 2067). 
T4 — Trifilar broadband transformer. 15 

trifilar turns of No. 26 enam. wire on 

Amidon T-50-61 toroid core. 
U2, U3 - RCA IC. 
VR1 - 9.1-V, 1-W Zener diode. 



444 



IF AMPLIFIER CIRCUITS 



445 



INPUT"—®- 



>€ 




3.5-4 MHz TUNABLE IF WITH NOISE BLANK- 
ING — MC1550G is followed by Silicon General 
SG3402T mixer that provides good conversion 



noise spikes for blanker consisting of 1N60 dual-gate MOSFET, transformer-coupled to ce- 
diode gate and 40673 pulse amplifier. Blanker is ramie filter FL2 at IF output. Article gives con- 
fed from envelope detector that controls gate struction details. — R. Megirian, The Minicom 



gain with very light oscillator loading. Mixer feeding FL1 dual ceramic filter providing IF se- Receiver, 73 Magazine, April 1977, p 136-149. 
output is fed to 40673 amplifier that builds up lectivity. IF stage following blanker uses SD304 



AGC-MGC 
TO SECOND 
CONVERTER 



455KHJ 

INPUT 

FROM 

SECONO 

CONVERTER 



AGC-MGC FROM 
MODE SWITCH 



455 KHz 
OUTPUT TO 
005 DETECTOR 

J!" 




455-kHz SECOND IF — Used in all-band double- gain amplifier using three MPS 2926 transistors 
conversion superheterodyne receiver for AM, all having automatic gain control and master 
narrow-band FM, CW, and SSB operation. Input gain control. Use of silicon rectifiers in inter- 
is fed through 455-kHz ceramic filter to high- stage networks of IF amplifier gives economical 



wide-range AGC circuit. Supply is 13.6 V regu- 
lated. Article gives all circuits of receiver. — D. 
M. Eisenberg, Build This All-Band VHF Receiver, 
73 Magazine, Jan. 1975, p 105-112. 



446 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+8V, 3mA 



1n 



l.F. Input 



330k 



TO-02 
Resonator 




BC169C 



0A90 

-44- 



▼ 0A90 J.' 



R 3 
10k 



2,200p 

2£00 p" 



R 4 
50k 



COUPLING TO HIGH-IMPEDANCE DETECTOR— 
Final IF stage of receiver uses piezoelectric over- 
tone resonator connected backwards for cou- 
pling to high-impedance detector. Arrange- 
ment provides useful voltage step-up as well, 
about 2.5 times. Resonator can be Brush Clevite 
Transfilter.— G. W. Short, Reversed Operation 
of Transfilter,' Wire/ess World, Aug. 1971, p 
386. 



o.g.c. 



-VvV- 

R 5 

39k 



V AGC © 



Input 

(so n) 




2 Vdc 



T-|: Primary - 15 turns. No. 22 AWG wire, T 2 : Primary - 10 turns, No. 22 AWG wire, 

%" I.D. Air Core Secondary — 4 turns. No. 22 AWG VS" I.D. Air Core Secondary — 2 turns. No. 22 AWG 

wire, coef. of coupling % 1.0 wire, coef . of coupling % 1 .0 

60 MHz WITH 80-dB POWER GAIN— Two-stage network. Overall bandwidth is 1.5 MHz. Resis- "A High Gain Integrated Circuit RF-IF Amplifier 

tuned IF amplifier achieves maximum gain and tors in series with AGC pins 2 of opamp stages with Wide Range AGC," Motorola, Phoenix, AZ. 

output signal swing capability by using differ- provide more efficient AGC action.— B. Trout, 1975, AN-513, p 8. 
ential-mode coupling for interstage apd output 



BANDWIDTH (3 JBI3KH2 

GAIN 67 dB 

E| N - RMS 

E OUT " DETECTED Rf) 




- , DETECTED 

2«K< ^:.01„F OUTPUT 



NPUT - 
O GAIN CONTROL VOLTAGE 

(GROUND FOR MAXIMUM GAIN) 



-O TO NE 510 PIN 5 



I I 

MILLER 2063 



455-kHz CASCODE IF— Sections of Signetics 
NE510A transistor array serve as active ele- 
ments for IF strip using standard transformers. 
Voltage gain is 66 dB when gain-control input 
is grounded. Alternate detector connection for 
including AGC is shown below. — "Signetics 
Analog Data Manual," Signetics, Sunnyvale, 
CA, 1977, p 746-747. 



IF AMPLIFIER CIRCUITS 



447 



COMPRESSOR 
10 „F 2H4J9I 




455-kHz IF WITH AF COMPRESSOR— Combi- 
nation of IF amplifier, audio compressor, tuna- 
ble audio filter, and audio output system oper- 
ates from single supply. Compressor and filter 
each use N5558V dual opamps or equivalent 
units. Tuning range of filter is about 500 to 2000 
Hz. IF input goes directly to pin 2 of LM373H. 
Use coupling capacitor to prevent shorting pin 
2 to ground and damaging IC. — R. Megirian, 
Design Ideas for Miniature Communications Re- 
ceivers, Ham Radio, April 1976, p 18-25. 




120-144 MHz — General-purpose amplifier can and up to 144 MHz for RF. Transistor type is not azine, Peterborough NH 03458, July 1974, p 55- 
be used around 120 MHz as microwave IF strip critical.— B. Hoisington, DC Isolation, 73 Mag- 62. 



435-KHl FILTER 




455 kHz WTTH PRODUCT DETECTOR— Bipolar detector produces output in audio range when 455-kHz IF transformer, and T3 is miniature 

transistor Q6 provides about 20-dB gain at 455 its inputs are 455-kHz IF signal and BFO signal audio transformer with 10K primary and 2Kcen- 

kHz, which is adequatefor handling wide range near 455 kHz. Transistors can be2N222,2N3641, ter-tap secondary <CT not used).— O. DeMaw 

of signal amplitudes without changing audio 2N4123, or equivalent. T1 is J. W. Miller 8814 and L. McCoy, Learning to Work with Semicon- 

gain setting in receiver without AGC. Product 455-kHz IF transformer/filter, T2 is miniature ductors, QST, Aug. 1974, p 26-30. 



448 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




IF FILTER FOR CW— Circuit acts like variable fil- 
ter having adjustable bandwidth, with enough 
gain to compensate for insertion loss in CW re- 



ceiver. Used to isolate weak CW signals despite 
noise and interference, as required in low- 
power amateur work. FET input is directly cou- 
pled to collector of HEP55 serving as Q-multi- 
plier regenerative amplifier. Transformer L1-L3 
provides feedback. Filter is connected in series 
with input end of IF strip, following 1 .2-kHz me- 
chanical filter. When two CW signals are re- 
ceived, one can be eliminated by adjusting CA 
to recenter passband of filter. Current drain of 
6 mA can be supplied by two 6-V batteries. For 
455-kHz IF, C is 470 pF, CA is 7-45 pF, and L1- 
L2-L3 are 12-115-24 turns No. 32 enamel on 
Amidon T44-15 core. — S. M. Olberg, Vari-Q Fil- 
ter, Ham Radio. Sept. 1973, p 62-65. 



I-F AMPLIFIER 

+15V 



28-MHz LOW-NOISE— Developed for use with 
2304-MHz balanced mixer. Provides required 
match between 50-ohm mixer output and input 
of 28-MHz IF amplifier in UHF receiver. Input and 
output connections are made with short 
lengths of RG-58/U coax. Noise figure is less 
than 1 .5 dB. — L. May and B. Lowe, A Simple and 
Efficient Mixer for 2304 MHz, QST, April 1974, 
p 15-19 and 31. 




J' 



I 28 -MHz 

, , I ^OUTPUT 



* All other pins grounded. 
T1 - Miller #8851 A or Equivalent. 
T2 - Miller #8807 or Equivalent. 
T3 - Turns ratio =1:1 
Q unloaded = 50 
T4 - Standard Ratio Detector 3. 1. #36231 
or Equwalei 




50 HFTtZ. 

— 6 AM Output 



FM Output 6 



AM/FM WTTH AGO— Operates from single +15 the other for AM component. External transis- furnished by diode detector.— "Integrated Cir- 

V supply. Standard 455-kHz IF is used for AM to tor is needed because MC1350 requires up to 0.2 cuit IF Amplifiers for AM/FM and FM Radios/' 

feed 1N34A diode detector. One output of mA of AGC drive and this is more than can be Motorola, Phoenix, AZ, 1975, AN-543 A, p 10. 
MC1350 is used for FM signal component and 



IF AMPLIFIER CIRCUITS 



449 



l-F AMPLIFIER 











r 



j 



33k 

-*vw — *vW- 

BFO 
TUNE 



IF WITH NOISE BLANKER— Addition of BFO and 
noise blanker to 455-kHz IF amplifier gives setup 
for testing new tuners and front ends. Two 
methods of coupling into amplifier are shown. 
LM373H IC with two Murata SFD-455D ceramic 
filters fulfills requirements for IF amplifier, de- 
tector, and AGC functions. — R. Megirian, De- 
sign Ideas for Miniature Communications Re- 
ceivers, Ham Radio, April 1976, p 18-25. 



T ATTENUATOR— When inserted between 
stages of IF amplifier, circuit acts as three-sec- 
tion attenuator with dynamic range greater 
than 60 dB. Can be controlled by positive volt- 
age from AVC system of receiver or manually 
with 100K pot. Use PIN diodes. — Super Circuits, 
73 Magazine, Aug. 1975, p 140. 



-71- 



TOI-F 
AMPLIFIER 



:;5in 



12V 
o 



2N2270 




l M F 

sin 



5 M F 



TO FOLLOWING l-F 
AMPLIFIER STAGE 



>>T0 
_^" VOLTAGE 



JlOOK 
♦ 12 V o — w v 



MANUAL GAIN lh 
CONTROL 



(^-^WV- 



-)h 



,|_ , — Imps 



U.UI U.U1 U.UI 

3 > 51 > " '^ 



All other pins grounded. 
T — Ratio Detector (Input impedar 



*1.5 k) G.I. #36231 or equivalent. 



Non-De-emphatit 
OOutput 




10.7-MHz IF for FM — Motorola dual MC1355 amplifier for FM receiver. MPS- H 04 discrete impedancesare235ohms. — "Integrated Circuit 
limiting gain blocks are used with two TRWfive- transistor is used afterfirst filter block to reduce IF Amplifiers for AM/FM and FM Radios/' Mo- 
pole linear phase filters and external ratio de- noisefigureforoverallsystem. Input and output torola. Phoenix, AZ, 1975, AN-543A, p 4. 
tector to give complete high-performance IF 



450 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




,-.(.1—0-0 
SVDC 



Q MULTIPLIER— Transistorized Q multiplier can 
be connected to plate of mixer in receiver hav- 
ing IF in range of 1400-1500 kHz. Iron-core coil 
should have high Q. Setting of pot depends on 
transistor used, which could also be HE-3 or 
2N1742.— Q& A, 73 Magazine, April 1977, p 165. 







NOTE: ENCIRCLED LETTERS DESIGNATE TEST POINTS 



and construction. — B. Hoisington, Building a 
135-kHz STRIP— Developed for use in all-band supply, connected to positive terminal of C11 135 kHz l-F Strip, 73 Magazine, Sept. 1975, p 
VHF/UHF/S-band receiver. Operates from 12-V through 100-ohm resistor. Article covers design 127-130 and 132. 



IF Input 

R S = 5° 15 pF __T 




,-p U.U1 /JN U.Ol /p 



Audio 

Output 

5.1 k 

•wv © 



-120pF 



T - Miller #8851 A or Equivalent. 



C.F. — Vernitron Ceramic Filter, Model FM-4 



FM AUTO RADIO IF— Uses MC1357 quadrature Sensitivity is 18 ftSI for 3% total harmonic dis- AM/FM and FM Radios," Motorola, Phoenix, AZ, 
detector after ceramic filter to give IF band- tortion.— "Integrated Circuit IF Amplifiers for 1975, AN-543A, p 6. 
width required for good stereo reproduction. 



IF AMPLIFIER CIRCUITS 



451 



-••5MA 
.01 CR2 .01 

H ( T W f If 



T1 
455 kHi 




.01 

U— OTO "2 
l-FAMP 



DIODE-SWITCHED IF FILTER— Used in 1.8-2 
MHz communication receiver having wide dy- 
namic range. 1N914 diodes select Collins me- 
chanical filter F4B5FD-04 FL3 (400-Hz band- 



width) or F455FD-25 FL4 (2.5-kHz bandwidth). main IF strip of receiver. Two-part article gives 

Reverse bias is applied to nonconducting all other circuits of receiver. — D. DeMaw, His 

diodes to lesson leakage through switching Eminence — the Receiver, QST, Part 1 — June 

diodes. Filter is located between IF preamp and 1976, p 27-30 (Part 2 — July 1976, p 14-17). 




10.7 MH/ IF TRANSFORMER 



BANDWIDTH - 300 KH, 
FOR FULL LIMITING 
E. n = 70 u VOLTS 



#u 



-I k" T 



Lp= 20 TURNS #36 
Ls = 20 TURNS #36 
TAPPED 5 TURNS 
FROM OUTER EDGE 



10.7-MHz LIMITING AMPLIFIER — Uses Signet- 300 kHz, achieved by adjusting transformers for pling. Full limiting is provided by circuit with 
icsNE510 transistor arrays in common-collector 600-kHz bandwidth and using dual cup-core input voltage of 70 /xVRMS. — "Signetics Ana- 
common-base configuration as IF strip for com- transformers originally designed for tubes. log Data Manual," Signetics, Sunnyvale, GA, 
mercial FM broadcast receiver. Bandwidth is Windings were changed to give critical cou- 1977, p 747-748. 



CHAPTER 40 

Instrumentation Circuits 



Includes DC, AF, and wideband RF amplifiers with such special features as 
automatic nulling and automatic calibration, for use with resistance-bridge, 
photocell, strain-gage, and other input transducers. Applications include 
measurement of ionization, radiation, small currents, liquid flow and level, 
light level, pH, power, torque, weight, and wind velocity. Metal detectors and 
proximity detectors are also covered. See also chapters covering 
measurement of Capacitance, Frequency, Resistance, and Temperature. 



0+15V 



0.47nF 




SCALE 

FACTOR 

ADJ 



ential current-to-voltage converter to obtain V ss 
WIND SPEED — Developed to give magnitude of voltages from strain-gage sensors are con- as sum-of-squares of V x and V Y . Range covered 
wind velocity over wide range of values when verted to normalized values V x and V Y which are is 1-1 00 mph. Article covers operation of circuit 
its two measured vectors are expressed as volt- squared by MC1495L four-quadrant transcon- in detail. — J. A. Connelly and M. B. Lundberg, 
ages. Output is in logarithmic form for easy ad- ductance multipliers. Output currents are then Analog Multipliers Determine True Wind Speed, 
aptation to data processors. N-S and E-W vector summed, and HA2705 opamp is used as differ- EDN Magazine, April 20, 1974, p 69-72. 



452 



INSTRUMENTATION CIRCUITS 



453 



12 Mn ■ 



100 pF 



d~ 1,500 pF 



© 

]— h_©J|n Q ' 
© 



4,700 pF 



|l2MJ2 J^Okfi 



33 Mfi > 12 Un 



KTH 



100 pF 1N3604 

-H— r 



1N3604-;r -r >3.3Mfi 

100 pF 



27 pF 
© 



'!-" 



© 



.Vdo 
(+9V) 







© 



H-i °« 
J® 



- OUTPUT 
(NORMALLY 
HIGH; GOES 
LOW TO 
INDICATE 
METAL 
OBJECT) 



PROXIMITY DETECTOR— Output changes from 
high (9 V) to low (0 V) when conducting object 
moves within 1 cm from open end of 150-turn 
coil L (No. 34 enamel) mounted in half of Fer- 
roxcube 181 1-PL00-3B7 core set. Can be used as 
contactless limit switch or tachometer pickup. 
Q,-0, are CMOS MOSFETs in CD4007A package. 
Q, and pickup coil form 100-kHz oscillator. 
Diodes develop DC voltage proportional to 
peak-to-peak value of oscillator signal, for ap- 
plication to Schmhtt trigger Q2-Q4. Conductive 
object near coil absorbs energy from magnetic 
field, lowering oscillator amplitude and turning 
Schmitt trigger off. 10K pot adjusts sensitivity. 
Circuit drives CMOS logic directly. For TTL 
drive, use buffer. — M. L. Fichtenbaum, Induc- 
tive Proximity Detector Uses Little Power, Elec- 
tronics, Jan. 22, 1976, p 1 12. 



0-15 MHz WITH 100-dB CMR— Differential in- 
puts are applied to Optical Electronics 9715 
opamp through 9714 voltage followers. Current 
booster using 9810 opamp raises load current 
to ±100 mA. Complete amplifier has very high 
differential and common-mode input imped- 
ance. Common-mode rejection can be trimmed 
to greater than 100 dB at 1 kHz for unity gain. 
Gain is determined by value of resistor RG con- 
nected between. points A and B and is equal to 
(2R2/R1)(1 + 2R2/RG). Settling time is 500 ns. 
Accuracy is maintained from -55°C to +85°C. — 
"Instrumentation Amplifier," Optical Electron- 
ics, Tucson, AZ, Application Tip 10240. 





A 
O 



5k 
R2 



100 5k 



COMMON 
MODE 
TRIM 



R2 



5k 

— vw- 
R2 




-Oe D 



5k 

-M/V- 

R2 



1 



0001|J. 



TO 1 _N_ 

probe \Jf7™ 




-+9V 



J. SOji 
^12V 



270 < 1 <? 'recorder 






MOSFET DIFFERENTIAL AMPLIFIER— Devel- 
oped to monitor chemical process of titration, 
by recording probe output voltages between 
100 and 400 mV when internal impedance of 
probe is in gigohm range. Either 40673 or 3N187 
dual-gate MOSFETs connected as differential 
amplifier are suitable for meeting high input re- 
sistance requirement. Transistor level drifts be- 
cause of temperature a re in opposition and tend 
to cancel each other. Overall power gain of am- 
plifier is about 70 dB. Circuit is suitable for other 
electrometer applications as well. — D. R. Bow- 
man, Automatic Titration Potentiometer, Wire- 
lass World, Aug. 1971, p 400-401. 



— 9V 



454 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ o 



R„>1.5kfi 




*-E„ S(E. -EJ 



AW 



HIGH GAIN WITH WIDE BANDWIDTH— High 
CMRR is achieved by using Q, and Q 2 as emitter- 
coupled pair biased by constant-current 
sources Q 3 and ft. Differential signals applied 
to Q, and Q 2 appear across 100K resistor R for 
amplification by factor inversely proportional to 
R g . R 5 is used to null opamp A, when no input 
is present. Bandwidth, determined by A„ is 
about 2 MHz. Gain is flat at about 40 dB over 
temperature range of -55°C to +125°C. Circuit 
will handle common-mode inputs up to ±10 
V.— W. G. Jung, "IC Op-Amp Cookbook," How- 
ard W. Sams, Indianapolis, IN, 1974, p 243-245. 



*R, varied to adjust input sensitivity and gain; can be 
greater than 200 Wl if attenuation desired. 



TORQUE WRENCH— Micro Networks MN2200 
instrumentation amplifier is used with strain 
gage to create digital-readout torque wrench. 
Strain gages having nominal impedance of 120 
ohms are bonded to torque-sensing member at 
45° to longitudinal axis, so gages in opposite 
bridge arms are under simultaneous tension or 
compression for given direction of torque. 
Bridge power is taken from 5-V digital panel 
meter supply. Instrumentation amplifier will 
work with any voltage from ±5 to ±15 V. Vari- 
able gain-adjust resistor G (10-turn 50K pot) is 
set so DPM reads 200 ft-lb of torque at full scale 
in increments of 0.1 ft-lb. — R. Duris, Instrumen- 
tation Amplifiers — They're Great Problem Solv- 
ers When Correctly Applied, EDN Magazine, 
Sept. 5, 1977, p 133-135. 



<+5V 




■±- +10V -10V 



ZERO ADJ. 




NOTES: 

•15V SUPPLIES BYPASSED TO GROUND WITH 5 „F CAPACITOR 
O, -Q t : CA3086 TRANSISTOR ARRAY IC 



0-35 MHz WITH GAIN OF 10 — Wideband am- sors. High-frequency gain is provided by 40673 back path establish amplifier gain. R 6 sets op- 

plifier handles inputs up to 100 mV P-P and dual-gate MOSFET. Low-frequency gain with erating point of N, for 10-mA drain current. Base 

drives 1-kilohm load, to meet requirements of DC stabilization is provided by CA3130 CMOS resistor of Q 3 is 1 kilohm. — H. A. Wittlinger, 

oscilloscope preamps, instrumentation and opamp. Transistors Q,-Q 5 are part of CA3086 CMOS Op Amp, MOSFET Implement Wideband 

pulse signal amplifiers, and video signal proces- transistor-array IC. Values of R 3 and R 4 in feed- Amplifier, EDN Magazine, June 20, 1977, p 1 14. 



INSTRUMENTATION CIRCUITS 



455 



3-18 V 



161 kHz 



VOLUME 



36 pF 




10 mH 



SEARCH COIL 
(AWG 18, 140 TURNS, 6IN. DIAMETER) 



%4030 




METER AMPLIFIER— Junction FET in simple DC 
amplifier circuit converts 0-1 mA DC milliam- 
meter to 0-100 jtA DC microam meter. Adjust 
zero-set control for zero meter current with no 
input, then apply input signal and adjust gain to 
desired value. — N. J. Foot, Electronic Meter 
Amplifier, Ham Radio, Dec. 1976, p 38-39. 



TWIN-OSCILLATOR METAL DETECTOR— Metal 
object near search coil changes frequency of 
oscillator A, which is initially tuned to 160 kHz, 
thereby changing frequency of 1-kHz output de- 
rived by mixing with 161-kHz output of A,. Sen- 
sitivity, determined largely by dimensions of 
search coil, is sufficient to detect coins about 1 
foot away. — M. E. Anglin, C-MOS Twin Oscil- 
lator Forms Micropower Metal Detector, Elec- 
tronics, Dec. 22, 1977, p 78. 



BRIDGE SENSITIVITY ADJUST 




+15V DC 
150 mA +, 

-o 



COMMON £j 



-15V DC Q 
<9> 150 mA^ 



12V DC 
INPUT 

i \ 



DC/DC 
CONVERTER 

MAIN 

STRAIN-GAUGE 

SYSTEM 

POWER SUPPLY 

STEVENS- 
ARNOLD 
A12/D15/150/Z 



-o 



SYSTEM 

OUTPUT 

1V, ±50 mA 



S 



STRAIN-GAGE AMPLIFIER— Optimum perfor- output stage. Bypass capacitors suppress un- VDC for system while giving excellent power 
mance is achieved in fully portable system by desirable high-frequency signals. Stevens-Ar- isolation.— D. Sheehan, Strain-Gauge Trans- 
utilizing combination of 747 opamps for A, and nold DC/DC converter operating from 12-V stor- ducer System Uses Off-the-Shelf Components, 
A 2 with National LH002CH opamp for B,-B 3 and age battery provides required regulated ±15 EDN Magazine, Nov. 5, 1977, p 79-81. 
special AD521K instrumentation amplifier for 



456 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




±34 V COMMON-MODE RANGE— Interconnec- 
tions shown for three LM143 high-voltage 
opamps give equivalent of single differential- 
input opamp having wide common-mode 
range, high input impedance, and gain of 1000. 
Adjust R2 to trim gain. Adjust R7 for best com- 
mon-mode rejection. With 10K load, frequency 
response is down 3 dB at 8.9 kHz. — "Linear Ap- 
plications, Vol. 2," National Semiconductor, 
Santa Clara, CA, 1976, AN-127, p 2-3. 



Vc = +38V 



1p^,C5 



DIFFERENTIAL-INPUT AMPLIFIER— Provides 
gain up to 1000, depending on value of Rg, for 
video signals in radar, medical ultrasound, laser - 1 NPUT 
communication, and laser rangefinder applica- 
tions. Uses three Optical Electronics 9906 wide- 
band opamps and 9910 current booster for 
cable drive. Bandwidth is above 10 MHz for 
gains of 0.1 to 100, decreasing to 5 MHz at gain 
of 1000. Miller compensation of input amplifiers 
minimizes noise level and gives input imped- 
ance of 5 megohms and 5 pF. — "Wide Band In- 
strumentation Amplifier," Optical Electronics, + input 
Tucson, AZ, Application Tip 10276. 



REMOTE 
SENSING 

9 




OUTPUT 



REFERENCE 

9 



GAIN»1+2k/Rg 



COMMON 




R6=300 

C3=0.3-2pF 

Ct-.033uF 





I 



lOOp 



K 



Phones 

Q 



:,0 W' KEM^ 

3[Dl > R 6 T Tr 5 



f • 



R 



c, 

4p7 



C10 ' 

6k8.? lOOn' 



10k < 



METAL DETECTOR— Will detect small coin up 
to about 5 inches underground and larger metal 
objects at much greater depths. Frequency of 
search oscillator Tr,-Tr 2 depends on values used 
for three paralleled capacitors, search coil, and 
metal objects in vicinity of coil. Mixer Tr 3 feeds 



difference between search oscillator and refer- 
ence oscillator Tr„-Tr 5 to opamp and Tr 6 for driv- 
ing phones or loudspeaker. Article gives con- 
struction and adjustment details, including 
dimensions for search coil. Reference oscillator 
is set to 625 kHz. C, is 560 pF, C 2 150 pF, and C 3 



10 pF variable. C 2 is used for coarse tuning, and 
C 3 for fine adjustment to get beat note. Diodes 
are 1N4148. Tr 3 is BC308, BCY72, or equivalent, 
and other transistors are BF238, BC108, or 
equivalent. — D. E. Waddington, Metal Detector, 
Wire/ess World, April 1977, p 45-48. 



INSTRUMENTATION CIRCUITS 



457 




50-OHM LINE DRIVER— CA31 00 bipolar MOS 
opamp operates as high-slew-rate wideband 
amplifier that provides 18 V P-P into open circuit 
or 9 V P-P into 50-ohm transmission line. Slew 
rate is 28 V//is. — "Circuit Ideas for RCA Linear 
ICs," RCA Solid State Division, Somerville, NJ, 
1977, p 13. 



NOMINAL BANDWIDTH =10 MHz 
t,= 35 ns 



ADJUSTABLE-GAIN WIDEBAND AMPLIFIER— 
Single resistor R8 adjusts gain from less than 1 
to over 1000, with gain value equal to 200,000 
divided by value in ohms used for R8. Common- 
mode rejection ratio is about 100 dB, indepen- 
dent of gain. Q1-Q2 are operated open-loop as 
floating differential input stage. Current 
sources Q3 and 04 set operating current of 
input transistors. — "Linear Applications, Vol. 
2," National Semiconductor, Santa Clara, CA, 
1976, LB-21. 



R6 
100k 



*INPUT O- 



_r-^W 




PICOAMMETER CIRCUIT 

lOKMn 




f M ) 500-0-500 ,.A 



OPAMP PICOAMMETER— Current-to-voltage guarded mode to reduce leakage current. handled with single 10,000-megohm resistor in 

converter connection for CA3160 and CA3140 CA3140 provides gain of 100 for driving zero- overall feedback path.— "Circuit Ideas for RCA 

bipolar MOS opamps provides full-scale meter center microammeter. With suitable switching. Linear ICs," RCA Solid State Division. Somer- 

deflection for ±3 pA. CA3160 is operated in full-scale current ranges of 3 pA to 1 nA can be ville, NJ, 1977, p 14. 



458 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 15V 

o 



PHOTODIODE 
INPUT 

X s 



©- 



ANALOG 
MULTIPLIER 




TO SUMMING AMPLIFIER 



-© 



.ins. 




AUTOMATIC CALIBRATOR— Automatic scaling 
circuit permits frequent and fast recalibration 
for precision optical measurements, to compen- 
sate for variations in light intensity due to ther- 
mal cycling of lamp filament, dirty optics, and 
gain variations between photodetectors and 
between amplifiers. With reset pulse at point B, 
comparator A 2 compares output of multiplier to 
preset reference voltage on R,. If A 2 input volt- 
age is greater than reference applied to pin 3 by 
R 2 , output switches to zero and remains there 
until d has discharged enough to lower output 
of A, and output of multiplier below reference 
on pin 3. If input at pin 2 of A 2 is less than ref- 
erence on pin 3, A 2 will switch to IS V and out- 
put of multiplier will be adjusted upward until 
voltage on pin 2 of A 2 again exceeds that on pin 
3. Output of A 2 is thus continually switching be- 
tween 1 5 V and V during reset or scaling. After 
reset pulse is removed, scale factor K is main- 
tained constant by multiplier during measur- 
ing. — R. E. Keil, Automatic Scaling Circuit for 
Optical Measurements, EDNIEEE Magazine, 
Nov. 15, 1971, p 49-50. 



HIGH GAIN FOR WEAK SIGNALS— National 
LM121 differential amplifier is operated open- 
loop as input stage for input signals up to ±10 
mV. Input voltage is converted to differential 
output current for driving opamp acting as cur- 
rent-to-voltage converter with single-ended 
output. R4 is adjusted to set gain at 1000. Null 
pot R3 serves for offset adjustment. — "Linear 
Applications, Vol. 2," National Semiconductor, 
Santa Clara, CA, 1976, AN-79, p 7-8. 




97.6k 



97.6k 
O «/W-±- 

SIGNAL 




A, THROUGH A, LM324N 
IC 5 LM311N 

S, CD4016 



0-20 Hz DATA DEMODULATOR— Used for 
measuring and monitoring suppressed-carrier 
signal modulation from aircraft control sys- 
tems. Provides data frequency response within 
0.1 dB from DC to 20 Hz, with linearity better 



I 5V 

than 0.1%. In-phase reference voltage applied 
to comparator IC 5 controls gating of CD4016 
MOS switch S,. Suppressed-carrier signal is 



buffered by opamp A, for branching to sum- 
ming junction of A 3 . Article describes operation 
of circuit. — J. A. Tabb and M. L. Roginsky, In- 
strumentation Signal Demodulator Uses Low- 
Power IC's, EDN Magazine, Jan. 20, 1976, p 80. 



INSTRUMENTATION CIRCUITS 



459 



OPTIONAL BYPASS NETWORK 
(SEE CHAPTER II 
PIN4 PIN7 

* ♦ 
.1. 




PHOTOCELL BRIDGE— Radio Shack 276-116 
cadmium sulfide photocell is connected in 
Wheatstone bridge circuit. When bridge is bal- 
anced, RS741C opamp connected to opposite 
corners of bridge receives no voltage and meter 
reads zero. Light on photocell unbalances 
bridge and gives meter deflection. Can be used 
as high-sensitivity light meter. Adjust R3 until 
meter reads zero with photocell covered while 



R5 is at maximum resistance, adjust R5 until 
needle moves away from zero, rezero with R3, 
and repeat procedure until meter can no longer 
be brought to zero. Sensitivity is now maxi- 
mum, and uncovered photocell will detect 
flame from candle at 20 feet. — F. M. Mims, "In- 
tegrated Circuit Projects, Vol. 4," Radio Shack, 
Fort Worth, TX, 1977, 2nd Ed., p 29-35. 






X 



HIGH INPUT Z— Suitable for use as active probe 
for CRO, as electrometer, and for instrumenta- 
tion applications. Combination of unipolar and 
bipolar transistors gives desirable amplifying 
features of each solid-state device. — I. M. Got- 
tlieb, A New Look at Solid-State Amplifiers, 
Ham Radio, Feb. 1976, p 16-19. 



SIX-RANGE LIGHT METER— Switching of feed- 
back resistors for opamp driven by Radio Shack 
276-1 15 selenium solar cell gives multirange lin- 
ear light meter. With 1000-megohm resistor for 
highest sensitivity, star Sirius will produce pho- 
tocurrent of about 25 pA when solar cell is 
shielded from ambient light with length of card- 
board tubing. Supplies are 9 V, and meter is 0- 
1 mA. — F. M. Mims, "Integrated Circuit Proj- 
ects, Vol. 4," Radio Shack, Fort Worth, TX, 1977, 
2nd Ed., p 45-53. 



ROTARY SWITCH 
275-1385 OR 275-1385 




LED4 




LED1 



LIGHT METER WITH LED READOUT— Light on 
phototransistor Q1 (Radio Shack 276-130) pro- 
duces voltage change across R2 for amplifica- 
tion by opamp whose output drives array of five 
LEDs forming bar graph voltage indicator. Ad- 
just R3 initially for highest sensitivity by turning 
off room lights and rotating until LED 1 just 
stops glowing. Now, as light is gradually in- 
creased on sensor, LEDs come on one by one in 
upward sequence and stay on until all five are 
lit. Solar cells or selenium cells can be used in 
place of phototransistor. — F. M. Mims, "Opto- 
electronic Projects, Vol. 1," Radio Shack, Fort 
Worth, TX, 1977. 2nd Ed., p 85-93. 



460 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ o- 
(Voltage Input) 



(Current Input) 



(Common) 




V (Full Scale) 


R„(!J 


R. («>) 


Ran) 


10 mV 


100 k 


1.5 M 


1.5 M 


100 mV 


1.0 M 


1.5M 


1.5 M 


1.0V 


10M 


1.5 M 


1.5 M 


10 V 


10 M 


300k 





100 V 


10 M 


30k 






NANOAMMETER— Programmable amplifier 
operating from ± 1.5 V supply such as D cells is 
used as current-to-voltage converter. Offset 
null of A, is used to minimize input offset volt- 
age error. If programmed for low bias current, 
amplifier can convert currents as small as 100 
nA with less than 1% error. Resistor values for 
variety of current and voltage ranges are given 



I (Full Scale) 


R,(!!) 


M'i) 


100 nA 


1.5 M 


1.5 M 


500 nA 


300 k 


300 k 


1.0 pA 


300k 





5.0 ^A 


60 k 





10mA 


30 k 





50 nA 


S.Ok 





100 mA 


3.0 k 






in tables. Adjust R, to calibrate meter, and ad- 
just R 2 to null input offset voltage on lowest 
range. Not suitable for higher current ranges 
because power drain is excessive above 100 
liA— W. G. Jung, "IC Op-Amp Cookbook," 
Howard W. Sams, Indianapolis, IN, 1974, p 414- 
417. 




FET-BIPOLAR DARLINGTON— Can be used as 
meter interface amplifier, impedance trans- 
former, coax driver, or relay actuator. Combi- 
nation of unipolar and bipolar transistors gives 
desirable amplifying f eatu res of each solid-state 
device. — I. M. Gottlieb, A New Look at Solid- 
State Amplifiers, Ham Radio, Feb. 1976, p 16- 
19. 



DIGITAL pH METER— 3130 CMOS opamp gives 
required high input impedance for pH probe at 
low cost. Output of probe, ranging from posi- 
tive generated DC voltage for low pH to V for 
pH 7 and negative voltages for high pH values, 
is amplified in circuit that provides gain adjust- 
ment to correct for temperature of solution 
being measured. For analog reading, output of 
opamp can be fed directly to center-scale mil- 
liammeter through 100K calibrating pot. For 
digital display giving reading of 7.00 for 0-V out- 
put, pH output is converted to calibrated cur- 
rent for summing with stable offset current 
equal to 700 counts. This is fed to current-to-fre- 
quency converter driving suitable digital dis- 
play. Standard pH buffer solutions are used for 
calibration. — D. Lancaster, "CMOS Cookbook," 
Howard W. Sams, Indianapolis, IN, 1977, p 347- 
349. 



"TEMPERATURE 1 



'ERATURE" f 

V* WW— 



18. 7K 1* | 8.66KM, 10K 5% 
15 meg* 



pH PROBE 
INPUT 



IBNC) 



SK 100K* 



USE SENSOREX 
t S100C PROBE 




CALIBRATE 



OR EQUIV t 1 

'KEEP LEADS OFF PC BOARD 



100K 



-Wv- 

47K 
3130 

WITH itL, 10 uF 

HEATSINK ^ 



100K 



1 
220K 
1,1 



DIGITAL 
DISPLAY 



CURRENT 

TO FREQUENCY 

CONVERTER 



J33K 



°, (+5V. -5V SUPPLIES! 
USE QUALITY BNC CONNECTOR "> v 



I ( ► Jj~n S58 



'1- 100 COUNTS PER pH UNIT 
'2 -700 COUNT OFFSET 



"STANDARDIZE" 
-5V< 



iTANDARDIZE" .■ 

,JC2 



100K 



; 1.2 meg 




E.=(E.-EJ 



'_5s_\ 

,10,000 J 

n. 
10,000 



* Matching of resistor pairs R 3 - R 
determine! CMRR. 



DIFFERENTIAL-INPUT VARIABLE-GAIN— Gain 
of A 3 is varied by modifying feedback returned 
to R„. A„ serves as active attenuator in feedback 
path, presenting constant zero-impedance 
source to R 4 as required for maintaining good 
balance and high CMRR. With values shown, 
gain can be varied from unity to 300. — W. G. 
Jung, "IC Op-Amp Cookbook," Howard W. 
Sams, Indianapolis, IN, 1974, p 238-239. 



INSTRUMENTATION CIRCUITS 



461 




SENSOR-BRIDGE AMPLIFIER— RCA CA3094 
combination power switch and amplifier can be 
used with variety of transducer bridges for in- 
strumentation and other applications. Circuit 
delivers output of 1 V full-scale for driving 
meter. Pot R serves as centering or reference 
control. Can be used as thermometer if one leg 
of bridge is thermistor and meter scale is cali- 
brated in degrees.— E. M. Noll, "Linear IC Prin- 
ciples, Experiments, and Projects," Howard W. 
Sams, Indianapolis, IN, 1974, p 311-313. 



HIGH CMRR — Use of two Precision Monolithics 
OP-05 opamps feeding OP-01 opamp gives 
input impedance of about 100 gigohms and 
high common-mode rejection for instrumenta- 
tion applications. — "Instrumentation Opera- 
tional Amplifier," Precision Monolithics, Santa 
Clara, CA, 1977, OP-05, p 7. 



Z m < IOOGQ 
[| N -tl.OnA 




R4 2kQ 

-AAA, — 



R6 20kQ 
-Wk 



R5 2kQ 
-AAA/ ' 




>20kQ 



SR" 2.5V/ p»c 

MATCHING 

REQUIRED 

TO REALIZE 

HIGH CMRR 



• R5 J 
■ R7 TT 



R6 / i 
R*(" 



R.«, Offset 1 



R. 

E. -O — VW- 



0, 

D.I1N914 




A 
V 



R : 

tOkll 
0.f% 



R,^154kl1 
'1.0% 



Rc,<27i! 



R. 
-^Wv — 

33.2 kll 
0.1% 



D,2 11N914 



MO kl! 
\ 1.0% 




R.>154kll 

'1.0% 
B 



I 



R, 

10 k!l 
270 II 0.1% 




-»-E = 



33.2 k|] 
0.1% 



±„«..« «»l* 



(E.-E.) 
R, = R. 
R, = R, 
R, = R, 

A 



?4*)fe) 



-( i 4r s, )(W*" 



' Matching of resistor pairs R, - R t and R, - R T determines 
CMRR. All gain resistor* (R, - R,| should be metal-lilmw 
wirewound types for best stability. 



DIFFERENTIAL PREAMP— Opamps A, and A 2 
form cross-coupled preamp with differential 
input and differential output, driving instru- 
mentation opamp A 3 to provide overall gain of 
106. Common-mode input range is ±10 V, and 
full-scale differential input is ±100 mV. For 
higher input impedance, 108 opamps can be 
used in preamp. For higher speed, all three 
opamps can be 118. — W. G. Jung, "IC Op-Amp 
Cookbook," Howard W. Sams, Indianapolis, IN, 
1974, p 241-243. 



462 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




LINEAR LIGHT METER— Uses Radio Shack 276- 
115 selenium solar cell or equivalent photocell 
with high-gain RS741C opamp to drive meter. 
Sensitivity is sufficient to detect individual stars 
at night without magnifying lens if photocell is 
shielded from ambient light with length of card- 
board tubing. Increasing value of R1 increases 
gain and sensitivity of circuit. R2 sets meter 
needle to zero when sensor is dark. — F. M. 
Mims, "Integrated Circuit Projects, Vol. 4," 
Radio Shack. Fort Worth, TX, 1977, 2nd Ed., p 
45-53. 



HODOSCOPE AMPLIFIER— Charge amplifier 
using Teledyne Philbrick 1 02601 opamp was de- 
veloped for use with each Geiger counter of 1 32- 
counter array for ionization hodoscope used in 
tracing paths of cosmic rays. Charge-sensitive 
stage A, converts input charge pulse to voltage 
pulse significantly larger than noise of second 
stage. With 616-pF load capacitor, output is 12 
V for input of 10 mV. Cost of charge amplifier is 
about $50. — H. C. Carpenter, Low Cost Charge 
Amplifier, EDN Magazine, May 20, 1973, p 83 
and 85. 



INPUT 




OUTPUT 



ALL RESISTORS 1/4 W 

C, 3kV SPRAGUE CERAMIC 30GA-D47 

C 2 100V MICA D 15 1E 100FC 

C 3 35 V SPRAGUE CS 13BF 105K 

A, 102601 TELEDYNE PHILIBRICK 

A 2 1026 TELEDYNE PHILBRICK 

C. DETECTOR LOAD CAPACITANCE 



0.5mH SEARCH COIL _ 

30T +6V O 

N0.26 i 




T^=a 



8V4IN.DIA. 



.0068 



F = lOOkHZ 



2N2222 
-L \|Q1 




.015 =; 



o.i 



4.7K . 



8 10 



; 12K 



-6VO- 




Tl 1 

20K ^ 01 S 



.001 

-K- 



565 



4.7K 



.0047 



680 



ZERO 






: 



50K 



GAIN 



-^vw- *■ 



IK 



<♦> 



tlOOMICRO AMP 



5.6K 



5.6K 



PLL DETECTOR FOR ALL METALS — Frequency increases when search coil is brought near non- when coil is brought near ferrous object. — "Sig- 
change produced in Colpitts oscillator by metal ferrous metal object. Oscillator frequency de- netics Analog Data Manual," Signetics, Sunny- 
object neartank coil is indicated by 565 PLL con- creases, as indicated by lower meter reading, vale, CA, 1977, p 856-858. 
nected as frequency meter. Oscillatorfrequency 



INSTRUMENTATION CIRCUITS 



463 




THREE-STAGE OPAMP— Responds to differ- 
ence between two applied signals. Differential 
output voltage of LM102 pair is applied to bal- 
anced differential input of LM107 opamp. Out- 
put can be metered or used in any other desired 
manner. Voltage gain is equal to ratio R4/R2 and 
is 100 for values shown. — E. M. Noll, "Linear IC 
Principles, Experiments, and Projects," Howard 
W. Sams, Indianapolis, IN, 1974, p 126. 



FEEDBACK OPAMP FOR BRIDGE— Uses 
CA3094 programmable opamp to convert dif- 
ferential input signal from resistor bridge to sin- 
gle-ended 1-V output signal. Circuit provides 
feedback for opamp. RC network between ter- 
minals 1 and 4 of opamp provides compensa- 
tion to improve stability. — "Circuit Ideas for 
RCA Linear ICs," RCA Solid State Division, So- 
merville, NJ, 1977, p 13. 




* SET TO OPTIMIZE CMRR 




CMOS LOGIC 
INPUT 
SELECT 
HIGH -DIFFERENCE IN B 



* — Ov 0UT 



Z5> 



DIGITALLY SELECTABLE INPUTS AND GAIN— 

Low-power DG306 and DG305 analog switches -isv -15 V 

provide choice of 10.4 or 101 gain and choice of tation applications. Highest gain is obtained and Their Applications," Silicon ix, Santa Clara, 

two differential input channels for instrumen- when control logic is high. — "Analog Switches CA, 1976, p 7-91. 



464 



MQDERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



OUTPUT 




_. 5Vpp1kHz 

J U U TEST SIGNAL 



FLOW METER — Simple opamp circuit with one 
transistor gives reliable hot-wire anemometer 
for measuring flow of gases or liquids. R 2 is 
heated above ambient temperature in Wheat- 
stone bridge including overheat resistor R, 
which is calibrated to be 30% larger than cold 
resistance of R 2 . Bridge is fed from power tran- 
sistor which is within feedback loop of opamp 
that senses bridge unbalance. Output of bridge 



is fed back to power transistor in correct phase 
for maintaining constant-temperature condi- 
tion in which R 2 is approximately equal to R,. 
Article covers construction of hot-wire probe 
made from Wollaston wire. — W. Bank, Build 
Your Own Constant-Temperature Hot-Wire 
Anemometer, EDN Magazine, Aug. 1, 1972, p 
43. 



o +3to+12v. 
{determined by the voltage the relay requires) 



TN4148 i I 




NONLATCHING RELAY- When liquid rises 
above level determined by positions of probes, 
circuit is triggered and relay, buzzer, or other 
indicator is energized. Alarm stops when liquid 
drops below preset level again. Use any oper- 
ating voltage from 3 to 12 V that will actuate 
load employed. — J. A. Sandler, 9 Easy to Build 
Projects under $9, Modern Electronics, July 
1978, p 53-56. 




CA3I40> — ($) i-fWV-i 

10 MJ2 



-i^vV 



SMALL-CURRENT AMPLIFIER— CA3140 bipolar 
MOS opamp serves as high-gain current ampli- 
fier. Input current through load is increased by 
ratio of R2 to R1, which is 1000 for values 
shown, for reading by meter M. Dashed lines 



show method of decoupling circuit from effects 
of high output-lead capacitance. — "Circuit 
Ideas for RCA Linear ICs," RCA Solid State Di- 
vision, Somerville, NJ, 1977, p 13. 




±IOVO — vw 



LARGE-SIGNAL BUFFER— Unity-gain connec- 
tion of Precision Monolithics OP-07A opamp 
provides high accuracy (0.005% worst case) 
over temperature range of -55°C to +125°C for 
buffer applications for ±10 V signals. — D. Sod- 
erquist and G. Erdi, "The OP-07 Ultra-Low Off- 
set Voltage Op Amp — a Bipolar Op Amp That 
Challenges Choppers, Eliminates Nulling," Pre- 
cision Monolithics, Santa Clara, CA, 1975, AN- 
13, p 8. 




'Selected 5pF to TOOpF 



400-Hz AMPLIFIER WITH 95-dB CMRR— Preci- 
sion Monolithics OP-10 dual opamp driving OP- 
02 opamp gives high common-mode rejection 
ratio. CMRR is optimized by selecting C1 and C2 
in range of 5 to 100 pF for minimum output e„ 



as viewed on CRO while feeding ±10 V signal 
at 400 Hz to common connection of inputs. — 
"Linear & Conversion I.C. Products," Precision 
Monolithics, Santa Clara, CA, 1977-1978, p 
15-2. 




PICOAMMETER — Highly stable circuit uses 
Valvo CSA70 chopper-stabilized opamp. Re- 
quired high feedback resistance is provided by 
R,-R 2 in feedback loop. Article gives design 
equations. R,' and R 2 are 1 megohm, R, is 10 
ohms, and all capacitors are 0.1 /»F. — K. Kraus, 
High-Speed Picoammeter, Wireless World, May 
1976, p 78. 



INSTRUMENTATION CIRCUITS 



465 



HEADPHONE JACK 




50 DC 
MICROAMMETER 



•DANGER! HIGH VOLTAGE 



GEIGER COUNTER — Output signal of Victoreen 
1B85 G-M tube biased at 900 VDC is propor- 
tional to beta-gamma particle count. Signal is 
amplified by high-gain AF amplifier Q1-Q2 for 
driving AC meter circuit. Closed-circuit Jack is 
provided for alternate use of headphones. 
Count-rate range of instrument is determined 
by exposing G-M tube to different calibrated ra- 
dioactive samples and marking meter scale for 
each. Bias for counter can be obtained from 
three 300-V photoflash batteries in series or 
equivalent supply capable of providing up to 10 
mA. — R. P. Turner, "FET Circuits," Howard W. 
Sams, Indianapolis, IN, 1977, 2nd Ed., p 152- 
153. 



DIFFERENTIAL TO SINGLE-ENDED— Conver- 
sion from differential input signal of thermo- 
couple to single-ended output signal is 
achieved without feedback by using CA3094A 
programmable opamp. Output is ±4.7 V at 8.35 
mA. Preamp gain is 180. For linear operation, 
differential input must be equal to or less than 
±26 mV. — "Circuit Ideas for RCA Linear ICs," 
RCA Solid State Division, Somerville, NJ, 1977, 
p13. 




ZERO & OFFSET 



VOLTAGE REFERENCE 



STRAIN OUAOES* 



r;: : 

5k '. 



i*i 



R. 
10, 
WW. 




(VOLTAGE 
OUTPUT 
ADJUST 



R, 

10k, WW. 

ZENER CURRENT ADJUST 



•1' 



^175 /: 



1N829 
IAGE0 & 
TESTEDI 



♦ 15VQ 



n 



17S 



H i \ 2N2905A X 

- 1 5V { T^F 



,(MW^ 



PREAMPLIFIER 



1M< R„, 



POWER SUPPLY # I 
(AD902I 



POWER SUPPLY « 2 
IAD902) 




POLYSTYRENE • 



R 
100k 



R U' 
too 



* R n 

id w.w. 



m 



Ih 



S, MADTS12DI) 
|-H0ffo 



fEXTERNAL OFFSET 



R„. 20k - 




-7h 




t. __________ 



<j-E 



lOJ FROM COMPUTER 
I llTARE WEIGHT] 



TARE WEIGHT 
LOGIC COMMAND 
ROM COMPUTER 



I 



ELECTROMAGNETIC 
& ELECTROSTATIC SHIELDS, 
PLUS STYROFOAM ENCLOSURE 
FOR THERMAL SHIELD 



NOTES: 

• - ULTRONIXTYPE 10SA Wl REWOUND 
"r - FLOATED GROUND 
ffl - INSTRUMENT (EDISON) GROUND 
" - 100k, 0.006*. TYPE R^. 
JULIE RESEARCH LABS 
"• - 600. 0.1*. R-44, JULIE RESEARCH LABS 

ALL OP AMPS AND POWER SUPPLIES • ANALOG DEVICES 
> - SCHEMATIC FOR STRAIN GUAGES IS SIMPLIFIED 

0.02% WEIGHING ACCURACY— Analog instru- 
ment covers up to 300 lb with resolution of 0.01 



lb, for monitoring changes in body weight dur- 
ing clinical study. Bonded strain gages distrib- 
uted symmetrically on platform of scale form 
bridge network R^Rz-Ri-Rs serving as input for 
circuit that displays weight on digital panel 
meter and provides digital outputs to com- 



puter. Proper grounding is critical; all ground 
returns should go to single point at each power- 
supply common line. Article covers circuit op- 
eration in detail. — J. Williams, This 30-PPM 
Scale Proves That Analog Designs Aren't Dead 
Yet, EDN Magazine, Oct. 5, 1976, p 61-64. 



466 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




HIGH-IMPEDANCE DIFFERENTIAL-INPUT— 
Two Harris HA-2900 chopper-stabilized opamps 
feed HA-2700 high-performance opamp for in- 
strumentation applications. Circuit provides ex- 
cellent rejection of ±10 V common-mode input 
signals. Protection diodes prevent voltages at 
input terminals from exceeding either power 
supply. Supply can be ±15 V. — "Linear & Data 
Acquisition Products," Harris Semiconductor, 
Melbourne, FL, Vol. 1, 1977, p 7-70 (Application 
Note 518). 



FERRITE-BEAD CURRENT TRANSFORMER— 
No. 27 ferrite bead (Ferronics 11-122-B) wound 
with 25 turns No. 30 enameled wire and 
shunted by 50-ohm VW resistor, gives low-cost 
transformer that can be used in range of 3 kHz 
to 30 MHz. Current-conversion ratio is 1 V/A into 
50-ohm coaxial-cable termination, with excel- 
lent linearity from milliamperes up into am- 
peres. Wire carrying current to be measured is 
passed once through core, to serve as single- 
turn primary of transformer. — M. Salvati, Fer- 
rite Bead Makes Cheap Current Transformer, 
EDN Magazine, March 20, 1974, p 85. 



NSULATING SLEEVE 

PRESS-FITTED 

INTO CORE. 




COVER WITH EPOXY 

CEMENT OR RIGID 

POTTING COMPOUND 



58U 



TYPICAL INPUT CIRCUIT 




10k 



SIGNAL 
INPUT 



STRAIN 
GAUGES 




REFERENCE 
NPUT 



10k 




OFFSET ZEROING LOOP 



10 



+ 15V 






_X£ 

\£ 

A mC1 O ll_l »" 



AD7513JH 



^ 



OUTPUT 



GND ' 



REFERENCE GROUND 



3.3k 



6.8k 



0.022 hF 




.390 



OUTPUT 
SIGNAL 



390 



0.022 V F 



AUTOMATIC NULLING — Simple offset zeroing mentation opamp A, to reference ground. Arti- input circuit using strain gages is shown at left 
loop reduces effective input offset of instru- cle describes operation in detail. Input signal of dashed line. — M. Cerat, Zeroing Loop Re- 
mentation amplifier to less than a microvolt by source drives logic input, for nulling up to 4 V duces Instrumentation Amplifier Offsets, EDN 
using zero-and-hold that nulls output of instru- without using external nulling pot. Typical Magazine, March 20, 1976, p 100 and 102. 



INSTRUMENTATION CIRCUITS 



467 



+6V 



C1 
50 pF 



INSTRUMENT 

SIGNAL 

INPUT 



.C2 
50 pF 



+6V 




JT 



Q1 



Q2 



C3_ 



R3 
70k 



Q3 



Q4 



2 mA 



+4V 



c 



Q5 



+2V 



V I FLOATING 



SIGNAL 
GROUND 



ANALOG PREAMP— Combination of 5-kHz FET- 
chopper amplifier Q1-Q2 with transformer iso- 
lation of signal and system grounds gives low- 
cost analog instrumentation amplifier that will 
process millivolt DC signals while rejecting 



TRANSFORMER DATA 




T1 


T2 


PRIMARY 


150T 


300T 


SECONDARY 


1650T 


aooT 


SECONDARY TAP AT 


120T 


- 


LAMINATIONS 


EE-28 —29 


CAPACITANCE: 


8 pF I 8 pF 


(PRIMARY to SECONDARY) 



C4 
1„F 



>R5 
'20k 



01,2,4.6,7,8 2N4221 

03, 5 GENERAL PURPOSE NPN 

CR1 . 2, 3, 4 GENERAL PURPOSE 

hundreds of volts of common-mode DC. Signal 
accuracy is 0.1% for inputs between 50 and 500 
mV. Input impedance is 4 megohms, drift is only 
0.2 /uV7°C, and DC common-mode rejection rate 
is better than 120 dB. Low-impedance output of 




TO SYSTEM 
_ C6 OR SHARED 

" 1 pF AMPLIFIER 



followers Q3-Q4-Q5 is sent through T1 to syn- 
chronous FET demodulator Q6-Q7. R7 adjusts 
system scaling. — C. A. Walton, High-CMR, Low- 
Cost DC Instrumentation Preamp, EDN Maga- 
zine, Jan. 15, 1971, p 47-48. 



+32 Vdc 




OP AMPS: 741 

*R 5 : 12 k£2(5%) FIXED, 5 kflVARIABLE 



POWER-TO-VOLTAGE TRANSDUCER— Two 
opamps and inexpensive IC multiplier provide 
output voltage directly proportional to instan- 



-15 V 



taneous power through load. Frequency re- 
sponse extends from DC to several kilohertz. 



13.7 kf2_L_ Maximum load powerfor linearity is 2 kVA, with 
maximums of 400 V and 5 A for load voltage and 
current. Output voltage can vary from -10 V to 
+10 V depending on instantaneous polarities 
and magnitudes of load voltage and current. R, 
determines current range, and R, determines 
voltage range. — D. DeKold, Integrated Multi- 
plier Simplifies Wattmeter Design, Electronics, 
Sept. 27, 1973, p 106-1 07; reprinted in "Circuits 
for Electronics Engineers," Electronics, 1977, p 
175-176. 



CHAPTER 41 

Integrator Circuits 



Provide output that is integral of input with respect to time. Special features 
include logic-reset, analog start/stop, fast dump, and fast recovery. 



INTEGRATE AND DUMP— Transistor is used as 
switch, without power supply. Simple RC inte- 
grator will dump (discharge C) completely in 
about 1 its when dump input is logic 1 (+5 V). 
Values of R and C determine time constant of 
integrator. Without power supply, circuit can 
only drive high-impedance load; for low-imped- 
ance load, add FET-input opamp such as Analog 
Devices 40J as buffer.— R. Riordan, Integrate 
and Dump Circuit Uses No Power Supply, EDN 
Magazine, Feb. 20, 1973, p 93. 



BUFFER 



©-W^w^ 



1N277 




ODUMP 



TIMING 



BIT TIME 
INPUT 



SWITCH DRIVE 




SWITCH DRIVE 



FAST DUMP SWITCH— Requires only 350 ns to 
dump 6-V output to level of 3 mV. Transistors 
are connected so one of them is biased in for- 
ward mode independently of output polarity. 
Both transistors turn on during dump interval. 



Transistor operating in forward mode deter- 
mines initial discharge rate until it saturates, 
after which inverted-mode transistor continues 
to discharge capacitor. Offset voltage error is 



only -25 /*V. Opamp is Analog Devices 120 or 
equivalent having unity-gain bandwidth above 
1 00 MHz and slew rate above 200 V/fis. — F. Tar- 
ico. Fast Bipolar Dump Switch Has Low Offset, 
EDN Magazine, Nov. 5, 1974, p 66. 



468 



INTEGRATOR CIRCUITS 



469 



R-, R 2 

100k 100k 

inputO— WV e WA— •■ 




^15V 



O output 



HIGH INPUT IMPEDANCE— Two-opamp con- 
nection shown gives input resistance of 200 
megohms and drift time of 90 min for to 10 
V. — N. G. Boreham, Op-Amp Integrator, Wire- 
less World, March 1977, p 42. 



O common 



0-15V 



FAST RECOVERY— Two diodes and two zeners 
clamp output of integrator below saturation 
level of opamp, making recovery time approxi- 
mately equal to slew rate. With values shown, 
integration time constant R 3 C, is 35.6 ms and 
output is clamped at +23 V. Output linearity is 
±1%, and threshold range of circuit is -3 V to 
-10 V. — K. S. Wong, Fast-Recovery Integrator 
with Adjustable Threshold, EEE Magazine, Aug. 
1970, p 77. 



15 V 



+23V 




+25V& 




ELIMINATING RINGING— High-Q bandpass in- 
tegrator reduces ringing significantly by ampli- 
fying AC input signal in two broadband differ- 
ential amplifier stages. A, and A 2 , before 
differentiation and selection by D, and D 2 . Input 
gate pulse P, and differentiated pulses drive 
AND logic that generates output pulse P s coin- 
cident with zero crossings of AC input. Leading 
edge of P s will always occur at first zero cross- 
ing after P, initiates gating action. If output 
drives balanced diode bridge, gating pedestal 
and AC signal transient are eliminated; high-Q 
bandpass integrator then has fast settling time, 
permitting faster repetition rates. — R. J. Turner, 
Reduce Integrator Transients with Synchro- 
nized Gate Signals, EDNIEEE Magazine, Jan. 15, 
1972, p 46-47. 



470 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



+ 15V 




>GATE 
INPUT 



TYPICAL 
INPUT SIGNAL 



10V PEAK 



0V. 



A. 



STORING INTEGRATOR OUTPUT— Modified 
sample-and-hold circuit with capacitive feed- 
back combines integrate, sample, and hold 
functions, for use in temporarily storing output 
of integrator. Integrating amplifier is 741 
opamp; for critical applications, FET opamp is 
preferable. — E. Crovella, Circuit Combines In- 
tegrate, Sample and Hold Functions, EDN Mag- 
azine, Oct. 20, 1974, p 90. 



GATE SIGNAL -15V. 



OUTPUT 



ov. 



TIME OF OPERATION OF 
RESET PUSH-BUTTON SWITCH 



10V PEAK 



r 



i_ 



JFET WITH AC COUPLING— Connection shown 
gives very high voltage gain. Use of CI as Miller 
integrator or capacitance multiplier allows sim- 
ple circuit to handle very long time constant. — 
"FET Databook," National Semiconductor, 
Santa Clara, CA, 1977, p 6-26-6-36. 



2 



-o»* 



1 — T *1 

I o.i „F 

. Hh 



R1 
INPUT O— -V*V 






-O OUTPUT 



1 



m 

■ItSMtt/REIET O 
CONTROl 



CONDITIO* V, 



PRECISION INTEGRATOR— Low input bias cur- 
rent of National LH0052 opamp makes it suita- 
ble for applications requiring long time con- 
stants. R1 is selected so total leakage current at 
summing mode is sufficiently smaller than sig- 
nal current to ensure required accuracy. R2 is 
included to protect input circuit during reset 





< I O OUTPUT 



transient but can be omitted for low-speed ap- 
plications. R3, used to balance resistance in in- 
puts, should be equal to sum of R2 and 1 00-ohm 
resistance of reset switch. — "Linear Applica- 
tions, Vol. 1," National Semiconductor, Santa 
Clara, CA, 1973, AN-63, p 1-12. 



INPUT O— VW 



AC-COUPLED JFET— Use of CI as Miller inte- 
grator or capacitance multiplier allows simple 
circuit to handle very long time constant while 
providing high voltage gain. Circuit also offers 
low distortion with low noise and high dynamic 
range.— "FET Databook," National Semicon- 
ductor, Santa Clara, CA, 1977, p 6-26. 



INTEGRATOR CIRCUITS 



471 



+15V 



ein 




RMS CONVERTER— Converts analog voltage to 
RMS equivalent by squaring operation followed 
by integration and square-rooting. Bipolar input 
signal is first converted into linear absolute 
value with Optical Electronics 9004 absolute- 
value module, as required for processing by 
5904 unipolar devices. Pots are used to estab- 
lish 10-V full-scale level. R|C| is integration time 
constant. — "Simple RMS Converter," Optical 
Electronics, Tucson, AZ, Application Tip 10246. 



ANALOG START/STOP AND RESET— One sec- 
tion of DG300 dual analog switch serves for dis- 
charging integrator capacitor C through R L 
when resetting integrator, with start/stop 
switch section being held open by control logic. 
When both switches are open, output of inte- 
grator is held. — "Analog Switches and Their 
Applications," Siliconix, Santa Clara, CA, 1976, 
p 7-81. 



-^-Ohe: 



START.STOP 




Ov„= l/Rc/V| N dt 



00 FOR 15 VOLT OUTPUT SWINGS 



V|NO- 



A 



L 



1 



V, DG200 Vp 



I 



<- 



O-t^ 



v 2 

T 



T 



1201! 

-wv- 



(lOOpF-lpF) 



RESFT AND HOLD -15 V 

HIGH = RESET 

NOTE: PIN CONNECTIONS SHOWN ARE FOR METAL CAN PACKAGE 




► 5.1 meg 



LOGIC-RESETTABLE INTEGRATOR— DG200 
CMOS analog switch serves for discharging in- 
tegrator capacitor C rapidly for high logic input 
pulse. Other section of switch disconnects in- 
tegrator from analog input when logic goes 
high. When logic input is returned to low, inte- 
grator is triggered. Diodes prevent capacitor 
from charging to over 15 V. — "Analog Switches 
and Their Applications," Siliconix, Santa Clara, 
CA, 1976, p 7-68. 



472 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 



□ CI □ CI 
_l _l _l _l 



V IN» 




BIPOLAR INPUT FOR V/F CONVERTER— Abso- 
lute-value integrator circuit gives effect of gen- 
erating negative frequencies when input signal 
is negative by making counter count up for pos- 
itive voltage and count down for negative volt- 
age. Diode types are not critical. — M. O. Paiva, 
"Applications of the 9400 Voltage to Frequency 
Frequency to Voltage Converter," Teledyne 
Semiconductor, Mountain View, CA, 1978, AN- 
10, p 3. 



ABSOLUTE VALUE CIRCUIT 



CHAPTER 42 

Intercom Circuits 



Covers one-way and two-way basic intercom circuits, four-station two-way 
system, induction receiver for paging, and private telephone system. Audio 
amplifier circuits suitable for intercoms are also giyen. 



AUDIO INDUCTION RECEIVER— Used to pick 
up audio signal being fed to low-impedance sin- 
gle-wire loop encircling room or other area to 
be covered. Pickup loop LI is 100-500 turns 
wound around plastic case of receiver. Opamp 
sections are from Motorola MC3401P or Na- 
tional LM3900 quad opamp. Supply can be 9-15 
V. Requires no FCC license. Can be used as pri- 
vate paging system if audio amplifier of trans- 
mitter has microphone input. — C. D. Rakes, "In- 
tegrated Circuit Projects," Howard W. Sams, 
Indianapolis, IN, 1975, p 23-25. 




>2.2K 

bi I — yn 
^H'l'l' — -j- — u 



TO HEAD- 
PHONE 
2K 



40 - 

SPKR 




"=a£ 



MICROPOWER ONE-WAY INTERCOM— Na- 
tional LM3909 IC operating from single 1.5-V 
cell serves as low-power one-way intercom 
suitable for listening-in on child's room and 
meeting other room-to-room communication 
needs. Battery drain is only about 15 mA. Per- 
son speaking directly into 3.2-ohm loudspeaker 
used as microphone delivers full 1 .4 V P-P signal 
to 40-ohm loudspeaker at listening location. — 
"Linear Applications, Vol. 2," National Semi- 
conductor, Santa Clara, CA, 1976, AN- 154, p 9. 



473 



474 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




CASCADED 741 OPAMPS— Two opamps in se- 
ries provide 80 dB of audio gain with bandwidth 
of about 300 to 6000 Hz. Gain of each opamp is 
set at 100. With three stages, bandwidth would 
be 5100 Hz. Output will drive loudspeaker at 
comfortable room level, if fed through 1-/xF non- 
polarized capacitor to output transformer hav- 
ing 500-ohm primary and 8-ohm secondary. — C. 
Hall, Circuit Design with the 741 Op Amp, Ham 
Radio. April 1976, p 26-29. 



2 W WITH IC — Inexpensive audio amplifier 
using 14-pin DIP provides adequate power for 
small audio projects and audio troubleshooting. 
Pins 3, 4, 5, 10, 11, and 12 are soldered directly 
to foil side of printed-wiring board used for con- 
struction, to give effect of heatsink. — J. Schultz, 
An Audio Circuit Breadboarder's Delight, CO, 
Jan. 1978, p 42 and 75. 




500/25 



i =^5/25 



-°— *-v n 



470 < 





. T v 


Amplifier 






output 




I 






~TH 


Speaker 








1 





8f2 




One I.Sv. 
battery 



Telephone 
set 



BEEPER — Private two-station telephone sys- 
tem for home requires only two wires between 
ordinary telephone sets, with 1.5-V battery in 
series with one line, but this voltage is not 
enough to actuate ringers in sets. Beeper in par- 
allel with each set, with polarity as shown, 
serves same purpose as ringer. 555 timer IC1 
turns on IC2 about once every 3 s, and IC2 then 
generates 1000-Hz beep for about 1 s as ringing 
signal. No switches are required, because tele- 
phone handsets provide automatic switching. 
When both telephones are hung up, 1.5-V bat- 
tery splits equally between beepers and result- 
ing 0.75 V is not enough to turn on Q1 in either 
set. When one telephone is picked up, beeper at 
other telephone receives close to 1.5 V and Q1 
turns on IC1 to initiate beeping call. When other 
telephone is picked up, beeping automatically 
stops because 1.5 V is again divided between 
sets. — P. Stark, Private Telephone: Simple 
Two-Station Intercom, Modern Electronics, 
July 1978, p 32-34. 



Telephone 
set 



INTERCOM CIRCUITS 



475 



P+12V 





1 W AT 6 V — Battery-operated power amplifier 
using National LM390 IC provides ample power 
for loudspeaker despite operation from 6-V 
portable battery. — "Audio Handbook," Na- 
tional Semiconductor, Santa Clara, CA, 1977, p 
4-41. 



BIDIRECTIONAL INTERCOM— Uses 759 power 
opamps to provide 0.5 W for 1 6-ohm loudspeak- 
ers. Crystal microphones feed NPN transistors 
that provide both in-phase and 180° out-of- 
phase signals. Balance-adjusting circuits of am- 
plifier cancel out the two signals, so only out-of- 
phase signal goes to receiving unit. Privacy 



TONE 

CONTROL 

j'Jv (OPTIONAL) '« 

switch across microphone eliminates audio 
feedback while listening. Article tells how to 
calculate heatsink requirements. — R. J. Apfel, 
Power Op Amps — Their Innovative Circuits and 
Packaging Provide Designers with More Op- 
tions, EON Magazine, Sept. 5, 1977, p 141-144. 





DIRECT-COUPLED AF — Combination of unipo- 
lar and bipolar transistors gives desirable am- 
plifying features of each solid-state device. Can 
be used as speech amplifier and for other low- 
level audio applications. — I. M. Gottlieb, A New 
Look at Solid-State Amplifiers, Ham Radio, Feb. 
1976, p 16-19. 




SINGLE IC WITH TRANSFORMERS— CA3020 
differential amplifier uses AF input transformer 
T1 to match loudspeakers (used as microphone) 
to higher input resistance of IC. AF output trans- 



former T2 similarly matches IC to loudspeakers 
operating conventionally. — E. M. Noll, "Linear 
IC Principles, Experiments, and Projects," How- 
ard W. Sams, Indianapolis, IN, 1974, p 100-101. 



AF OUTPUT — Operates directly from 125-V rec- 
tified AC line voltage. Combination of unipolar 
and bipolar transistors gives desirable ampli- 
fying features of each solid-state device. — I. M. 
Gottlieb, A New Look at Solid-State Amplifiers, 
Ham Radio, Feb. 1976, p 16-19. 



476 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




0.25-W AMPLIFIER— Single Radio Shack RS386 
IC powered by 6-9 V from battery provides gain 
of about 200 with sufficient power to drive 8- 
ohm loudspeaker when speaking closely into 
small dynamic microphone of type used with 
portable tape recorders. — F. M. Mims, "Inte- 
grated Circuit Projects, Vol. 2," Radio Shack, 
Fort Worth, TX, 1977, 2nd Ed., p 87-95. 




(stations 2 - 
identical) 



Po-<p 
>" a — >^ 



-»• M, 





Ha, 







l£>i 



S, • 

s 3 - 



IC, 


CD4071 


IC 8 


CD401 1 


IC 2 


CD4081 


't-9 io 


CD4025 


ic 3 


CD4075 


A, 


LM380 


IC 4 


CD4028 


A 2 


741 


ic 56 , 


CD4016 






Station 








links 


Code 






1 to 2 


001 






1 to 3 


010 






1 to 4 


011 






2 to 3 


100 






2 to 4 


101 






3 to 4 


110 







FOUR-STATION TWO-WAY— Each station can 
communicate privately with any one of others. 
All four stations have identical inputs as at 
upper left, with fourth station having master 
circuit. Each two-station combination is as- 
signed 3-bit code as given in table, for selection 
by switches Sw,-Sw 4 . All station codes are 
ORed and decoded by IC 4 to drive matrix of an- 
alog switches for coupling appropriate audio in- 
puts and outputs. Code 000 is used for system- 



free status as indicated by LEDs 1 and 4 being 
on. LEDs flash for system-busy status. When 
code is selected, enable inputs of nonselected 
stations go low to prevent generation of further 
codes. System can be expanded to six stations 
by using 4-bit code and CD4514 decoder with 
larger matrix of analog switches. — B. Voyno- 
vich. Multiple Station Two-Way Intercom, Wire- 
less World, March 1978, p 59. 



INTERCOM CIRCUITS 



477 








2 




1 


J- 






™^S2 5M 






T ■ 


f T1 


25 1 









SINGLE OPAMP— When switch S1 is in talk po- 
sition as shown, loudspeaker of master station 
acts as microphone, driving opamp through 
step-up transformer T1. Switch at remote sta- 
tion must then be in listen position. Supply volt- 
age range is 8-20 V. — "Audio Handbook," Na- 
tional Semiconductor, Santa Clara, CA, 1977, p 
4-21-4-28. 



Vs(*l2V) 



2-W LM380 POWER AMPLIFIER— Complete 
basic circuit for most audio or communication 
purposes uses minimum of external parts. C3, 
used to limit high frequencies, can be in range 
of 0.005 to 0.05 fiF. — A. MacLean, How Do You 
Use ICs7, 73 Magazine, June 1977, p 184-187. 



JT 



047 IOmF 



X 



OI M F 



50-500/xF/I5-50V 




4 I6 OHMS 



GREEN 




0.5-W AF IC — Simple audio power stage drives 
8-ohm loudspeaker for producing greater vol- 
ume with pocket radio or for intercom applica- 
tions. Supply range is 4-12 V. For long life, 6-V 
lantern batteries are recommended. Trans- 
former is Radio Shack 273-1380. — F. M. Mims, 
"Integrated Circuit Projects, Vol. 5," Radio 
Shack, Fort Worth, TX, 1977, 2nd Ed., p 38-44. 



v s O 



HIGH-GAIN INTERCOM— Internal bootstrap- 
ping in National LM388 audio power amplifier 
IC gives output power levels above 1 W at sup- 
ply voltages in range of 6-12 V, with minimum 
parts count. AC gain is set at about 300 V7V, 
eliminating need for step-up transformer nor- 
mally used in intercoms. Optional RC network 
suppresses spurious oscillations. — "Audio 
Handbook," National Semiconductor, Santa 
Clara, CA. 1977, p 4-37-4-41. 




478 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




6 TO 18 VOLTS 



LOW-Z INPUT — Can be used with low-imped- 
ance source, such as 4- to 16-ohm loudspeaker 
or telephone earphone used as mike. If loud- 
speaker is put out in yard, sensitivity is suffi- 
cient to pick up sounds made by prowlers. Can 
be fed into input of any high-fidelity amplifier. — 
E. Dusina, Build a General Purpose Preamp, 73 
Magazine, Nov. 1977, p 98. 



411 to soon 



CHAPTER 43 

Keyboard Circuits 



Includes interface circuits required for converting keyboard operation to 
ASCII, BCD, hexadecimal, teleprinter, Baudot, Morse code, and other formats 
serving as inputs for microprocessors, PROMs, CW transmitters, hard-copy 
printers, TV typewriters, and other code-driven applications. See also 
Microprocessor and Telephone chapters. 




PULSE GENERATOR 




6 6 666 6 

T R r A 



ELECTRONIC TELETYPE KEYBOARD— Uses 
eight 7474 shift register sections in combination 
with pulse generator that is discharged through 
appropriate toroid core to create correct mark- 
space coding for energizing magnet drivers of 




-\0-< 



Teletype. Developed to permit communication be used at 60 WPM, adjust R1 so 555 oscillates 

by handicapped people. Simplified keyboard at 45 Hz. Toroids are Indiana General CF-102 

has one set of alphabetic characters and five having 10-turn primaries. — L. A. Stapp, Elec- 

numerics for BCD input. Outputs of shift regis- tronic Teleprinter Keyboard, Ham Radio, Aug. 

ters drive 7430 NAJMD gate U2. H keyboard is to 1978, p 56-57. 



479 



480 



MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL 




SCANNING ASCII ENCODER— Converts key ac- 
tion into composite parallel ASCII code. Circuit 
includes debouncing and two-key rollover. Two 
4001 quad two-input NOR gate sections form 
50-kHz clock that is gated. When clock is al- 
lowed to run, two cascaded 4520 binary 
counters are driven for continuous cycling 
through all their counts. Slower counter pro- 
duces 1-of-8 decoded output for 4051 l-of-8 
switch. Faster counter drives second switch 
that monitors sequential rows of characters. 
When key is pressed, output from +5 V through 
both selectors stops gated oscillator and holds 
count. Resulting ASCII output is then routed to 
external output logic for control and shift op- 
erations. When key is released, scanning re- 
sumes and continues until new key is pressed. 
If second key is pressed before first is released, 
nothing happens until first key is released. 
Scanning then resumes and stops at second key 
location, to give two-key rollover permitting 
faster typing with minimum error. — D. Lancas- 
ter, "CMOS Cookbook," Howard W. Sams, In-